diff --git a/src/Message/AbstractRequest.php b/src/Message/AbstractRequest.php
index b0d8da6..fbc9bec 100644
--- a/src/Message/AbstractRequest.php
+++ b/src/Message/AbstractRequest.php
@@ -2,12 +2,11 @@
 
 namespace Omnipay\Paystack\Message;
 
-use Omnipay\Common\Exception\BadMethodCallException;
 use Omnipay\Common\Exception\InvalidRequestException;
 
 abstract class AbstractRequest extends \Omnipay\Common\Message\AbstractRequest
 {
-    protected $baseApiEndpoint = 'https://api.paystack.co/';
+    protected $baseApiEndpoint = 'https://api.paystack.co';
 
     /**
      * @return string The URL endpoint for the request
diff --git a/src/Message/CompletePurchaseRequest.php b/src/Message/CompletePurchaseRequest.php
index 637f5e4..538acd9 100644
--- a/src/Message/CompletePurchaseRequest.php
+++ b/src/Message/CompletePurchaseRequest.php
@@ -11,7 +11,7 @@ class CompletePurchaseRequest extends AbstractRequest
      */
     public function getApiEndpoint()
     {
-        return $this->baseApiEndpoint . 'transaction/verify/' . rawurlencode($this->getTransactionReference());
+        return '/transaction/verify/' . rawurlencode($this->getTransactionReference());
     }
 
     /**
@@ -28,12 +28,11 @@ public function getData()
     public function sendData($data)
     {
         try {
-            $response = $this->sendRequest('GET', $this->getApiEndpoint(), json_encode($data));
+            $response = $this->sendRequest('GET', $this->getApiEndpoint(), $data);
         } catch (\Exception $e) {
-            
             throw new InvalidRequestException($e->getMessage(), $e->getCode(), $e);
         }
 
-        return $this->response = new CompletePurchaseResponse($this, $responseData);
+        return $this->response = new CompletePurchaseResponse($this, $response);
     }
 }
\ No newline at end of file
diff --git a/src/Message/PurchaseRequest.php b/src/Message/PurchaseRequest.php
index 27f8407..70d9712 100644
--- a/src/Message/PurchaseRequest.php
+++ b/src/Message/PurchaseRequest.php
@@ -11,7 +11,7 @@ class PurchaseRequest extends AbstractRequest
      */
     public function getApiEndpoint()
     {
-        return $this->baseApiEndpoint . '/transaction/initialize/';
+        return '/transaction/initialize';
     }
 
     /**
@@ -26,7 +26,9 @@ public function getData()
 
         return [
             'amount' => $amount,
+            'currency' => $this->getCurrency(),
             'email' => $email,
+            'reference' => $this->getTransactionReference(),
             'callback_url' => $this->getReturnUrl(),
             'metadata' => $this->getParameter('metadata')
         ];
diff --git a/src/Message/RefundRequest.php b/src/Message/RefundRequest.php
index 5f15eca..82c458e 100644
--- a/src/Message/RefundRequest.php
+++ b/src/Message/RefundRequest.php
@@ -11,7 +11,7 @@ class RefundRequest extends AbstractRequest
      */
     public function getApiEndpoint()
     {
-        return $this->baseApiEndpoint . '/refund';
+        return '/refund';
     }
 
     /**
@@ -19,13 +19,12 @@ public function getApiEndpoint()
      */
     public function getData()
     {
-        $amount = $this->getAmountInteger();
-        $reference = $this->getTransactionReference();
+        $data = [];
+        $data['transaction'] = $this->getTransactionReference();
+        $data['currency'] = $this->getCurrency();
 
-        $data = ['transaction' => $reference];
-
-        if ($amount) {
-            $data['amount'] = $amount;
+        if ($this->getAmountInteger()) {
+            $data['amount'] = $this->getAmountInteger();
         }
 
         return $data;