diff --git a/README.md b/README.md
index 3c12195..8cc32df 100644
--- a/README.md
+++ b/README.md
@@ -19,16 +19,16 @@ var paystack = require('paystack')('secret_key');
 The resource methods accepts are promisified, but can receive optional callback as the last argument.
 
 ```js
-// First Option
-// paystack.{resource}.{method}
+// First Option (with callback)
+// paystack.{resource}.{method}(callback)
 paystack.customer.list(function(error, body) {
   console.log(error);
   console.log(body);
 });
 ```
 ```js
-// Second Option
-// paystack.{resource}
+// Second Option (as promise)
+// paystack.{resource}.{method}.then().catch()
 paystack.customer.list()
 	.then(function(body) {
   		console.log(body);
@@ -40,7 +40,28 @@ paystack.customer.list()
 
 
 
-For resource methods that use POST or PUT, the JSON body can be passed as the first argument.
+For GET endpoints with url path parameters (e.g. https://api.paystack.co/plan/{id_or_plan_code}), pass path parameter as string or number
+Separate path parameter values by comma if more than 1 path parameter and place them in order as they appear in the url path.
+
+```js
+paystack.plan.get(90)
+  .then(function(error, body) {
+    console.log(error);
+    console.log(body);
+  });
+```
+
+For GET endpoints with query string parameters (e.g. https://api.paystack.co/bank/resolve?account_number=0022728151&bank_code=063), pass paramaters as object.
+
+```js
+paystack.bank.resolve_account_number({account_number: '0022778151', bank_code: '063'})
+  .then(function(error, body) {
+    console.log(error);
+    console.log(body);
+  });
+```
+
+For POST or PUT endpoints, the JSON body should be passed as the first argument.
 
 ```js
 paystack.plan.create({
@@ -54,25 +75,18 @@ paystack.plan.create({
 	});
 ```
 
-For GET, you can pass the required ID as string and optional parameters as an optional object argument.
-
-```js
-paystack.plan.get(90)
-	.then(function(error, body) {
-		console.log(error);
-		console.log(body);
-	});
-```
+For POST or PUT endpoints, if the endpoint also has path parameters (e.g. https://api.paystack.co/customer/{id_or_customer_code}), pass the path parameters as explained above, before passing the JSON body object.
 
 ```js
-paystack.transactions.list({perPage: 20})
-	.then(function(error, body) {
-		console.log(error);
-		console.log(body);
-	});
+var customer_id = 100;
+paystack.customer.update(customer_id, {last_name: 'Kehers'})
+  .then(function(error, body) {
+     console.log(error);
+    console.log(body);
+  });
 ```
 
-### Resources
+### Resources and Methods
 
 - customer
   - create
@@ -108,11 +122,31 @@ paystack.transactions.list({perPage: 20})
   - list
   - listBanks
   - update
+- bank
+  - list
+  - resolveAccountNumber
+  - resolveBin
 - Miscellanous
   - list_banks
   - resolve_bin
-  
 
+To use any endpoint, call 
+```js
+//using callback function
+paystack.{resource}.{method}(function(err, body){
+  console.log(error);
+  console.log(body);
+});
+
+//or as promise
+paystack.{resource}.{method}
+  .then(function(body) {
+      console.log(body);
+  })
+  .catch(function(error) {
+    console.log(error);
+  });
+```
 
 ### Contributing
 - To ensure consistent code style, please follow the [editorconfig rules](http://obem.be/2015/06/01/a-quick-note-on-editorconfig.html) in .editorconfig
diff --git a/index.js b/index.js
index 529eaf0..4a1e739 100644
--- a/index.js
+++ b/index.js
@@ -5,9 +5,10 @@ Paystack API wrapper
 
 'use strict';
 
-var
+var 
     request = require('request'),
-    root = 'https://api.paystack.co',
+    baseUrl = 'https://api.paystack.co',
+    acceptedMethods = [ "get", "post", "put" ],
     Promise = require('promise')
 ;
 
@@ -19,7 +20,8 @@ var resources = {
   subscription: require('./resources/subscription'),
   subaccount: require('./resources/subaccount'),
   settlements: require('./resources/settlements'),
-  misc: require('./resources/misc')
+  misc: require('./resources/misc'),
+  bank: require('./resources/bank')
 }
 
 function Paystack(key) {
@@ -27,15 +29,16 @@ function Paystack(key) {
     return new Paystack(key);
   }
 
-  this.key = key;
+  this.key = key || process.env["PAYSTACK_SECRET_KEY"];
   this.importResources();
 }
 
 Paystack.prototype = {
 
-  extend:  function(params) {
+  extend:  function(endpoint) {
   	// This looks more sane.
-    var self = this;
+    var secretKey = this.key;
+
     return function(){
       // Convert argument to array
       var args = new Array(arguments.length);
@@ -44,90 +47,88 @@ Paystack.prototype = {
         args[i] = arguments[i];
       }
 
-      // Check for callback & Pull it out from the array
+      // Check if last argument is supplied and is a valid callback function & Pull it out from the array
       var callback = l > 0 && typeof args.slice(l-1)[0] === "function" ? args.splice(l-1)[0] : undefined;
 
-      var body, qs;
-
-      // quick fix - method checking
-      var method = params.method in {"get":'', "post":'', "put":''}
-                 ? params.method
-                 : (function () { throw new Error("Method not Allowed! - Resource declaration error") })()
-      var endpoint = [root, params.endpoint].join('');
-      // Checking for required params;
-      if(params.params) {
-        var paramList = params.params;
-
-        // Pull body passed
-        var body = args.length === 2 ? args[1] : args[0];
-        paramList.filter(function(item, index, array) {
-          if(item.indexOf("*") === -1) {
-            // Not required
-            return;
-          }
-          item = item.replace("*", "");
-
-          if(!(item in body)) {
-            throw new Error("Required Parameters Ommited - " + item);
-          }
-          return;
-
-        });
+      // method checking
+      if (acceptedMethods.indexOf(endpoint.method) < 0) {
+        throw new Error("Method  - " + endpoint.method + " - not Allowed! - Resource declaration error")
       }
 
-      // Get arguments in endpoint e.g {id} in customer/{id} and pull
-      // out from array
-      var argsInEndpoint = endpoint.match(/{[^}]+}/g);
+      var method = endpoint.method;
+      var url = [baseUrl, endpoint.path].join('');
+
+      // First check path parameters (e.g {id} in customer/{id}) before checking post body or query string paramters
+      // Pull out all path parameters from url into array
+      var argsInEndpoint = url.match(/{[^}]+}/g);
       if (argsInEndpoint) {
         l = argsInEndpoint.length;
 
         // Do we have one or more?
         if (l > 0) {
-          // Confirm resource declaration good
-          if (!Array.isArray(params.args)) {
-            // error
-            throw new Error('Resource declaration error');
-          }
-
           // Confirm user passed the argument to method
           // and replace in endpoint
-
-          var match, index;
           for (var i=0;i<l;i++) {
-            match = argsInEndpoint[i].replace(/\W/g, '');
-            index = params.args.indexOf(match);
-            if (index != -1) {
-              if (!args[index]) {
-                // error
-                throw new Error('Resource declaration error');
-              }
-
-              // todo: args[index] must be string or int
-              endpoint = endpoint.replace(new RegExp(argsInEndpoint[i]), args[index]);
-              args.splice(index, 1);
+            //get the argument name from the path defined in resource
+            var argumentName = argsInEndpoint[i].replace(/\W/g, '');
+
+            if (!args[i]) {
+              // caller did not pass in this particular argument
+              throw new Error('Required path parameter ommited - ' + argumentName);
             }
+
+            //args[index] must be string or int
+            var argumentValue = args[i];
+            var valueType = typeof argumentValue;
+            if (valueType !== 'string' && valueType !== 'number') {
+              throw new Error('Invalid path parameter argument for ' + argumentName + '. Expected string or number. Found ' + valueType);
+            }
+
+            url = url.replace(new RegExp(argsInEndpoint[i]), argumentValue);
           }
+
+          //we've replaced all url path parameters with values from args
+          //now delete all such used values from args leaving only the optional qs/body parameters as first argument (if exist) in args
+          args.splice(0, l);
         }
       }
 
-      // Add post/put/[delete?] body
-      if (args[0]) {
+      var body, qs;
+
+      // Checking for required params;
+      if(endpoint.params) {
+        var parametersList = endpoint.params;
+        var parametersReceived = args[0]; //should now be first argument, having removed all path arguments
+
+        parametersList.filter(function(parameterName, index, array) {
+          if(parameterName.indexOf("*") === -1) {
+            // Not required
+            return;
+          }
+          parameterName = parameterName.replace("*", "");
+
+          if(!(parameterName in parametersReceived)) {
+            throw new Error("Required parameter ommited - " + parameterName);
+          }
+          return;
+        });
+
         if (method == 'post' || method == 'put') {
           // Body
-          body = args[0];
+          body = parametersReceived;
         }
         else if (method == 'get') {
-          qs = args[0];
+          qs = parametersReceived;
         }
       }
 
       // Make request
       var options = {
-        url: endpoint,
+        url: url,
         json: true,
         method: method.toUpperCase(),
         headers: {
-          'Authorization': ['Bearer ', self.key].join('')
+          'Authorization': ['Bearer ', secretKey].join('')
         }
       }
 
@@ -144,7 +145,6 @@ Paystack.prototype = {
             reject(error);
           }
           else if(!body.status){
-          
             // Error from API??
             error = body;
             body = null;
@@ -169,16 +169,22 @@ Paystack.prototype = {
   },
 
   importResources: function() {
-    var anon;
+    var resourceFunction, resource;
     // Looping over all resources
-    for (var j in resources) {
+    // each resource contains a collection of endpoints
+    for (var resourceName in resources) {
+      //get the resource object
+      resource = resources[resourceName];
       // Creating a surrogate function
-      anon = function(){};
-      // Looping over the properties of each resource
-      for(var i in resources[j]) {
-        anon.prototype[i] = this.extend(resources[j][i]);
+      resourceFunction = function(){};
+
+      // Looping over the endpoints of each resource
+      // each endpoint contains information for validating and calling the endpoint
+      for(var endpoint in resource) {
+        resourceFunction.prototype[endpoint] = this.extend(resource[endpoint]);
       }
-      Paystack.prototype[j] = new anon();
+
+      Paystack.prototype[resourceName] = new resourceFunction();
     }
   }
 };
diff --git a/resources/bank.js b/resources/bank.js
new file mode 100644
index 0000000..6c39305
--- /dev/null
+++ b/resources/bank.js
@@ -0,0 +1,26 @@
+'use strict';
+
+var root = '/bank';
+
+module.exports = {
+    /*
+        List supported banks
+    */
+    list: {
+        method: 'get',
+        path: root,
+        params: ['perPage', 'page']
+    },
+
+    resolveAccountNumber: {
+        method: 'get',
+        path: [root, '/resolve'].join(''),
+        params: ['account_number*', 'bank_code*']
+    },
+
+    resolveBin: {
+        method: 'get',
+        path: '/decision/bin/{bin}'
+    }
+
+}
diff --git a/resources/customer.js b/resources/customer.js
index 4ba12be..dd9846d 100644
--- a/resources/customer.js
+++ b/resources/customer.js
@@ -10,7 +10,7 @@ module.exports = {
   */
   create: {
       method: 'post',
-      endpoint: root,
+      path: root,
       params: ['first_name', 'last_name', 'email*', 'phone']
     },
 
@@ -19,8 +19,7 @@ module.exports = {
   */
   get: {
       method: 'get',
-      endpoint: [root, '/{id}'].join(''),
-      args: ['id']
+      path: [root, '/{id}'].join('')
   },
 
   /*
@@ -28,7 +27,7 @@ module.exports = {
   */
   list: {
       method: 'get',
-      endpoint: root
+      path: root
     },
 
   /*
@@ -37,9 +36,8 @@ module.exports = {
   */
   update: {
       method: 'put',
-      endpoint: [root, '/{id}'].join(''),
-      params: ['first_name', 'last_name', 'email', 'phone'],
-      args: ['id']
+      path: [root, '/{id}'].join(''),
+      params: ['first_name', 'last_name', 'email', 'phone']
     },
 
   /*
@@ -48,7 +46,7 @@ module.exports = {
   */
   setRiskAction: {
     method: 'post',
-    endpoint: [root, '/set_risk_action'].join(''),
+    path: [root, '/set_risk_action'].join(''),
     params: ['customer*', 'risk_action']
   }
 };
diff --git a/resources/misc.js b/resources/misc.js
index 328a32e..b192dc5 100644
--- a/resources/misc.js
+++ b/resources/misc.js
@@ -1,4 +1,4 @@
-	'use strict';
+'use strict';
 
 // Miscellanous functions have different endpoints
 
@@ -9,14 +9,13 @@ module.exports = {
 	*/
 	list_banks: {
 		method: 'get',
-		endpoint: '/bank',
+		path: '/bank',
 		params: ['perPage', 'page']
 	},
-	
+
 	resolve_bin: {
 		method: 'get',
-		endpoint: '/decision/bin/{id}',
-		args: ['id']
+		path: '/decision/bin/{bin}'
 	}
-	
+
 }
diff --git a/resources/page.js b/resources/page.js
index 7b82553..2b03faf 100644
--- a/resources/page.js
+++ b/resources/page.js
@@ -9,7 +9,7 @@ module.exports = {
   */
   create: {
       method: 'post',
-      endpoint: root,
+      path: root,
       params: ['name*', 'description', 'amount']
     },
 
@@ -18,8 +18,7 @@ module.exports = {
   */
   get: {
       method: 'get',
-      endpoint: [root, '/{id}'].join(''),
-      args: ['id']
+      path: [root, '/{id}'].join('')
   },
 
   /*
@@ -27,7 +26,7 @@ module.exports = {
   */
   list: {
       method: 'get',
-      endpoint: root
+      path: root
     },
 
   /*
@@ -35,17 +34,16 @@ module.exports = {
   */
   update: {
       method: 'put',
-      endpoint: [root, '/{id}'].join(''),
-      params: ['name', 'description', 'amount', 'active'],
-      args: ['id']
-    }, 
-   
+      path: [root, '/{id}'].join(''),
+      params: ['name', 'description', 'amount', 'active']
+    },
+
    /*
    Check Slug Avaliability
    */
   slug: {
-  	 method: 'get', 
-  	 endpoint: [root, '/check_slug_availability'].join(''),
-  	 params: ['slug*'] 	
+  	 method: 'get',
+  	 path: [root, '/check_slug_availability'].join(''),
+  	 params: ['slug*']
   }
 };
diff --git a/resources/plan.js b/resources/plan.js
index 5709e2c..66da505 100644
--- a/resources/plan.js
+++ b/resources/plan.js
@@ -9,7 +9,7 @@ module.exports = {
   */
   create: {
       method: 'post',
-      endpoint: root,
+      path: root,
       params: ['name*', 'description', 'amount*', 'interval*', 'send_invoices', 'send_sms', 'hosted_page', 'hosted_page_url', 'hosted_page_summary', 'currency']
     },
 
@@ -18,8 +18,7 @@ module.exports = {
   */
   get: {
       method: 'get',
-      endpoint: [root, '/{id}'].join(''),
-      args: ['id']
+      path: [root, '/{id}'].join('')
   },
 
   /*
@@ -27,7 +26,7 @@ module.exports = {
   */
   list: {
       method: 'get',
-      endpoint: root
+      path: root
     },
 
   /*
@@ -35,8 +34,7 @@ module.exports = {
   */
   update: {
       method: 'put',
-      endpoint: [root, '/{id}'].join(''),
-      params: ['name', 'description', 'amount', 'interval', 'send_invoices', 'send_sms', 'hosted_page', 'hosted_page_url', 'hosted_page_summary', 'currency'],
-      args: ['id']
+      path: [root, '/{id}'].join(''),
+      params: ['name', 'description', 'amount', 'interval', 'send_invoices', 'send_sms', 'hosted_page', 'hosted_page_url', 'hosted_page_summary', 'currency']
     }
 };
diff --git a/resources/settlements.js b/resources/settlements.js
index 34aeeb4..747697e 100644
--- a/resources/settlements.js
+++ b/resources/settlements.js
@@ -9,6 +9,6 @@ module.exports = {
   */
   fetch: {
       method: 'get',
-      endpoint: root,
+      path: root,
   }
 };
diff --git a/resources/subaccount.js b/resources/subaccount.js
index 5b62d6e..d2f371c 100644
--- a/resources/subaccount.js
+++ b/resources/subaccount.js
@@ -10,7 +10,7 @@ module.exports = {
   */
   create: {
       method: 'post',
-      endpoint: root,
+      path: root,
       params: ['business_name*', 'settlement_bank*', 'account_number*', 'percentage_charge*']
     },
 
@@ -19,8 +19,7 @@ module.exports = {
   */
   get: {
       method: 'get',
-      endpoint: [root, '/{id_or_slug}'].join(''),
-      args: ['id_or_slug']
+      path: [root, '/{id_or_slug}'].join('')
     },
 
   /*
@@ -28,7 +27,7 @@ module.exports = {
   */
   list: {
       method: 'get',
-      endpoint: root
+      path: root
     },
 
   /*
@@ -36,7 +35,7 @@ module.exports = {
   */
   listBanks: {
       method: 'get',
-      endpoint: '/bank'
+      path: '/bank'
     },
 
   /*
@@ -45,8 +44,7 @@ module.exports = {
   */
   update: {
       method: 'put',
-      endpoint: [root, '/{id_or_slug}'].join(''),
-      params: ['business_name', 'settlement_bank', 'account_number', 'percentage_charge'],
-      args: ['id_or_slug']
+      path: [root, '/{id_or_slug}'].join(''),
+      params: ['business_name', 'settlement_bank', 'account_number', 'percentage_charge']
     }
 };
diff --git a/resources/subscription.js b/resources/subscription.js
index 7ceef8f..95a434c 100644
--- a/resources/subscription.js
+++ b/resources/subscription.js
@@ -9,7 +9,7 @@ module.exports = {
   */
   create: {
       method: 'post',
-      endpoint: root,
+      path: root,
       params: ['customer*', 'plan*', 'authorization']
     },
 
@@ -18,7 +18,7 @@ module.exports = {
   */
   disable: {
       method: 'post',
-      endpoint: root,
+      path: root,
       params: ['code*', 'token*']
     },
 
@@ -27,7 +27,7 @@ module.exports = {
   */
   enable: {
       method: 'post',
-      endpoint: root,
+      path: root,
       params: ['code*', 'token*']
     },
 
@@ -36,8 +36,7 @@ module.exports = {
   */
   get: {
       method: 'get',
-      endpoint: [root, '/{id_or_subscription_code}'].join(''),
-      args: ['id_or_subscription_code']
+      path: [root, '/{id_or_subscription_code}'].join('')
   },
 
   /*
@@ -45,7 +44,7 @@ module.exports = {
   */
   list: {
       method: 'get',
-      endpoint: root
+      path: root
     }
 
 };
diff --git a/resources/transaction.js b/resources/transaction.js
index f0e4d0a..df928b2 100644
--- a/resources/transaction.js
+++ b/resources/transaction.js
@@ -9,7 +9,7 @@ module.exports = {
   */
   initialize: {
       method: 'post',
-      endpoint: [root, '/initialize'].join(''),
+      path: [root, '/initialize'].join(''),
       params: ['reference', 'amount*', 'email*', 'plan']
     },
 
@@ -18,7 +18,7 @@ module.exports = {
   */
   export: {
       method: 'get',
-      endpoint: [root, '/export'].join(''),
+      path: [root, '/export'].join(''),
       params: ['from', 'to', 'settled', 'payment_page']
     },
 
@@ -27,7 +27,7 @@ module.exports = {
   */
   charge: {
       method: 'post',
-      endpoint: [root, '/charge_authorization'].join(''),
+      path: [root, '/charge_authorization'].join(''),
       params: ['reference', 'authorization_code*', 'email*', 'amount*']
     },
 
@@ -36,7 +36,7 @@ module.exports = {
   */
   chargeToken: {
       method: 'post',
-      endpoint: [root, '/charge_token'].join(''),
+      path: [root, '/charge_token'].join(''),
       params: ['reference', 'token*', 'email', 'amount']
     },
 
@@ -45,8 +45,7 @@ module.exports = {
   */
   get: {
       method: 'get',
-      endpoint: [root, '/{id}'].join(''),
-      args: ['id']
+      path: [root, '/{id}'].join('')
   },
 
   /*
@@ -54,7 +53,7 @@ module.exports = {
   */
   list: {
       method: 'get',
-      endpoint: root
+      path: root
     },
 
   /*
@@ -62,7 +61,7 @@ module.exports = {
   */
   totals: {
       method: 'get',
-      endpoint: [root, '/totals'].join('')
+      path: [root, '/totals'].join('')
     },
 
   /*
@@ -70,8 +69,7 @@ module.exports = {
   */
   verify: {
       method: 'get',
-      endpoint: [root, '/verify/{reference}'].join(''),
-      args: ['reference']
+      path: [root, '/verify/{reference}'].join('')
     },
 
 };
diff --git a/test/bank.js b/test/bank.js
new file mode 100644
index 0000000..90a0db5
--- /dev/null
+++ b/test/bank.js
@@ -0,0 +1,58 @@
+var paystack = require('../index')(process.env.KEY)
+  , mocha = require('mocha')
+  , expect = require('chai').expect
+  ;
+
+describe("Paystack Bank Related Functions", function() {
+
+  // List Banks
+  it("should list all supported banks", function(done) {
+    paystack.bank.list()
+      .then(function(body){
+        expect(body).to.have.property('data');
+        expect(body.data[0]).to.have.property('name');
+        done();
+      })
+      .catch(function(error){
+        return done(error);
+      });
+  });
+
+  // Resolve a Bin Card
+  it("should resolve an account number", function(done) {
+    var queryParams = {
+      account_number: '0022728151',
+      bank_code: '063'
+    };
+    paystack.bank.resolveAccountNumber(queryParams)
+      .then(function(body){
+        /** uncomment following 3 lines if above details are valid **/
+        // expect(body).to.have.property('data');
+        // expect(body.data).to.have.property('account_number');
+        // expect(body.data).to.have.property('account_name');
+
+        /** comment out following 2 lines if above details are valid **/
+        expect(body).to.have.property('status');
+        expect(body).to.have.property('message');
+        done();
+      })
+      .catch(function(error){
+        return done(error);
+      });
+  });
+
+  // Resolve a Bin Card
+  it("should resolve a card bin", function(done) {
+    paystack.bank.resolveBin(539983)
+      .then(function(body){
+        expect(body).to.have.property('data');
+        expect(body.data).to.have.property('bin');
+        expect(body.data).to.have.property('card_type');
+        done();
+      })
+      .catch(function(error){
+        return done(error);
+      });
+  });
+
+});
diff --git a/test/customer.js b/test/customer.js
index 2a7e41c..df73cff 100644
--- a/test/customer.js
+++ b/test/customer.js
@@ -8,13 +8,13 @@ describe("Paystack Customers", function() {
   var customer_id;
 
   // New Customer
-  it("should create a new customer", function(done) {
+  it("create a new customer", function(done) {
     paystack.customer.create({
         first_name: 'Opeyemi',
         last_name: 'Obembe',
         email: 'kehers@gmail.com'
       })
-      .then(function(body){
+      .then(function(body){        
         expect(body).to.have.property('data');
         expect(body.data).to.have.property('id');
         customer_id = body.data.id;
@@ -26,16 +26,16 @@ describe("Paystack Customers", function() {
   });
 
   // To test callback & then chaining
-  it("create new customer, parse in callback and enter then handler", function(done) {
+  it("create a new customer, parse in callback and enter then handler", function(done) {
     paystack.customer.create({
        first_name: 'Opeyemi',
        last_name: 'Obembe',
       email: 'kehers@gmail.com'
     }, function(error, body) {
     	// callback should parse response and return an object
-    	return {'name': 'subomi'};
+      return {'name': 'subomi'};
     }).then(function(body) {
-     // callback is called, but then handler does not show its processing, but returns initial api response
+     // callback is called, and it returns a processed that to the then handler
     	expect(body).to.have.property('name')
     	done();
     }).catch(function(error) {
@@ -60,9 +60,9 @@ describe("Paystack Customers", function() {
   it("should get a customer's details", function(done) {
     paystack.customer.get(customer_id)
     .then(function(body){
+      done();
       expect(body).to.have.property('data');
       expect(body.data).to.have.property('id');
-      done();
     })
     .catch(function(error){
       return done(error);