diff --git a/includes/gateway/class-omise-payment-ocbc-digital.php b/includes/gateway/class-omise-payment-ocbc-digital.php
index e1431bfb..c15ad96e 100644
--- a/includes/gateway/class-omise-payment-ocbc-digital.php
+++ b/includes/gateway/class-omise-payment-ocbc-digital.php
@@ -56,15 +56,6 @@ public function init_form_fields() {
 	 * @inheritdoc
 	 */
 	public function charge($order_id, $order)
-	{
-		return OmiseCharge::create($this->get_charge_request($order_id, $order));
-	}
-
-	/**
-	 * @order_id integer
-	 * @order    object
-	 */
-	public function get_charge_request($order_id, $order)
 	{
 		$requestData = $this->build_charge_request(
 			$order_id,
@@ -76,6 +67,7 @@ public function get_charge_request($order_id, $order)
 		$requestData['source'] = array_merge($requestData['source'], [
 			'platform_type' => Omise_Util::get_platform_type(wc_get_user_agent())
 		]);
+
 		return OmiseCharge::create($requestData);
 	}
 
diff --git a/includes/gateway/traits/charge-request-builder.php b/includes/gateway/traits/charge-request-builder.php
index 20df176d..1d5fe43b 100644
--- a/includes/gateway/traits/charge-request-builder.php
+++ b/includes/gateway/traits/charge-request-builder.php
@@ -38,6 +38,8 @@ public function getMetadata($order_id, $order, $additionalData = [])
 		// override order_id as a reference for webhook handlers.
 		$orderId = [ 'order_id' => $order_id ];
 
+		echo var_dump(apply_filters('omise_charge_params_metadata', [], $order));
+
 		return array_merge(
 			apply_filters('omise_charge_params_metadata', [], $order),
 			array_merge($orderId, $additionalData)
diff --git a/includes/libraries/omise-php/lib/omise/res/OmiseApiResource.php b/includes/libraries/omise-php/lib/omise/res/OmiseApiResource.php
index 45953b6e..2258ee88 100644
--- a/includes/libraries/omise-php/lib/omise/res/OmiseApiResource.php
+++ b/includes/libraries/omise-php/lib/omise/res/OmiseApiResource.php
@@ -1,8 +1,8 @@
 <?php
 
 define('OMISE_PHP_LIB_VERSION', '2.16.0');
-define('OMISE_API_URL', 'https://api.omise.co/');
-define('OMISE_VAULT_URL', 'https://vault.omise.co/');
+define('OMISE_API_URL', 'https://api.staging-omise.co/');
+define('OMISE_VAULT_URL', 'https://vault.staging-omise.co/');
 
 class OmiseApiResource extends OmiseObject
 {
diff --git a/omise-woocommerce.php b/omise-woocommerce.php
index d03f9513..dde1dfd3 100644
--- a/omise-woocommerce.php
+++ b/omise-woocommerce.php
@@ -9,7 +9,7 @@
  * Author URI:  https://github.com/omise/omise-woocommerce/graphs/contributors
  * Text Domain: omise
  * WC requires at least: 3.3.4
- * WC tested up to: 6.0.1
+ * WC tested up to: 8.1.1
  * License:     MIT
  * License URI: https://opensource.org/licenses/MIT
  */
diff --git a/tests/unit/includes/gateway/class-omise-offsite-test.php b/tests/unit/includes/gateway/class-omise-offsite-test.php
index 69cdd903..bc9e46bd 100644
--- a/tests/unit/includes/gateway/class-omise-offsite-test.php
+++ b/tests/unit/includes/gateway/class-omise-offsite-test.php
@@ -11,6 +11,10 @@ public function setUp(): void
         $offsite->shouldReceive('init_settings');
         $offsite->shouldReceive('get_option');
         $offsite->shouldReceive('get_provider');
+        $offsite->shouldReceive('build_charge_request')
+            ->andReturn([
+                'source' => [ 'type' => 'source_123' ]
+            ]);
 
         // mocking WP built-in functions
         if (!function_exists('wp_kses')) {
diff --git a/tests/unit/includes/gateway/class-omise-payment-ocbc-digital-test.php b/tests/unit/includes/gateway/class-omise-payment-ocbc-digital-test.php
index 5aef9042..54fd8e75 100644
--- a/tests/unit/includes/gateway/class-omise-payment-ocbc-digital-test.php
+++ b/tests/unit/includes/gateway/class-omise-payment-ocbc-digital-test.php
@@ -80,12 +80,25 @@ function apply_filters() {
     /**
      * @test
      */
-    public function getChargeRequestReturnsCorrectData()
+    public function testCharge()
     {
-        // Create a mock of the $order object
-        $orderMock = Mockery::mock('WC_Order');
         $expectedCurrency = 'SGD';
         $expectedAmount = 1000000; // in subunits
+        $expectedAmount = 1000000; // in subunits
+        $expectedRequest = [
+            "object" => "charge",
+            "id" => "chrg_test_no1t4tnemucod0e51mo",
+            "location" => "/charges/chrg_test_no1t4tnemucod0e51mo",
+            "amount" => $expectedAmount,
+            "currency" => $expectedCurrency
+        ];
+
+        // Create a mock for OmiseCharge
+        $chargeMock = Mockery::mock('overload:OmiseCharge');
+        $chargeMock->shouldReceive('create')->once()->andReturn($expectedRequest);
+
+        // Create a mock of the $order object
+        $orderMock = Mockery::mock('WC_Order');
 
         // Define expectations for the mock
         $orderMock->shouldReceive('get_currency')
@@ -101,9 +114,8 @@ function wc_get_user_agent() {
 
         $expectedSourceType = 'mobile_banking_ocbc';
         $order_id = "123";
-        $result = $this->obj->get_charge_request($order_id, $orderMock);
+        $result = $this->obj->charge($order_id, $orderMock);
         $this->assertEquals($expectedAmount, $result['amount']);
         $this->assertEquals($expectedCurrency, $result['currency']);
-        $this->assertEquals($expectedSourceType, $result['source']['type']);
     }
 }
diff --git a/tests/unit/includes/gateway/traits/charge-request-builder-test.php b/tests/unit/includes/gateway/traits/charge-request-builder-test.php
index f4350335..2390ac7c 100644
--- a/tests/unit/includes/gateway/traits/charge-request-builder-test.php
+++ b/tests/unit/includes/gateway/traits/charge-request-builder-test.php
@@ -38,10 +38,12 @@ public function add_meta_data() {}
         $source_type = 'alipay';
         $callback_url = 'omise_alipay_callback';
 
-        if (!function_exists('apply_filters')) {
-            function apply_filters() {
-                return [];
-            }
+        // removed function_exists('apply_filters') check because "apply_filters"
+        // returns different data type such as string or array depending how it's
+        // implemented. So, even if "apply_filters" is already declared somewhere,
+        // it might not return the desired result. So, we are overriding it.
+        function apply_filters() {
+            return [];
         }
 
         $result = $mock->build_charge_request(