diff --git a/api/v3/Mjwpayment.php b/api/v3/Mjwpayment.php
index 81ac13fda62e20fb27a6ec972f9004ee75265f91..f9dff9415c19204dc74fd140f1b7578439cb4338 100644
--- a/api/v3/Mjwpayment.php
+++ b/api/v3/Mjwpayment.php
@@ -26,18 +26,46 @@
  *   Array of parameters determined by getfields.
  */
 function _civicrm_api3_mjwpayment_get_contribution_spec(&$params) {
-  $params['contribution_test'] = [
-    'api.default' => 0,
-    'type' => CRM_Utils_Type::T_BOOLEAN,
-    'title' => 'Get Test Contributions?',
-    'api.aliases' => ['is_test'],
+  $params = [
+    'contribution_test' => [
+      'api.default' => 0,
+      'type' => CRM_Utils_Type::T_BOOLEAN,
+      'title' => 'Get Test Contributions?',
+      'api.aliases' => ['is_test'],
+    ],
+    'trxn_id' => [
+      'name' => 'trxn_id',
+      'type' => CRM_Utils_Type::T_STRING,
+      'title' => ts('Transaction ID'),
+      'description' => ts('Transaction id supplied by external processor. This may not be unique.'),
+      'maxlength' => 255,
+      'size' => 10,
+      'where' => 'civicrm_financial_trxn.trxn_id',
+      'table_name' => 'civicrm_financial_trxn',
+      'entity' => 'FinancialTrxn',
+      'bao' => 'CRM_Financial_DAO_FinancialTrxn',
+      'localizable' => 0,
+      'html' => [
+        'type' => 'Text',
+      ],
+    ],
+    'order_reference' => [
+      'name' => 'order_reference',
+      'type' => CRM_Utils_Type::T_STRING,
+      'title' => 'Order Reference',
+      'description' => 'Payment Processor external order reference',
+      'maxlength' => 255,
+      'size' => 25,
+      'where' => 'civicrm_financial_trxn.order_reference',
+      'table_name' => 'civicrm_financial_trxn',
+      'entity' => 'FinancialTrxn',
+      'bao' => 'CRM_Financial_DAO_FinancialTrxn',
+      'localizable' => 0,
+      'html' => [
+        'type' => 'Text',
+      ],
+    ],
   ];
-
-  $params['financial_type_id']['api.aliases'] = ['contribution_type_id'];
-  $params['payment_instrument_id']['api.aliases'] = ['contribution_payment_instrument', 'payment_instrument'];
-  $params['contact_id'] = $params['contribution_contact_id'] ?? NULL;
-  $params['contact_id']['api.aliases'] = ['contribution_contact_id'];
-  unset($params['contribution_contact_id']);
 }
 
 /**
@@ -50,79 +78,38 @@ function _civicrm_api3_mjwpayment_get_contribution_spec(&$params) {
  *   Array of contributions, if error an array with an error id and error message
  */
 function civicrm_api3_mjwpayment_get_contribution($params) {
-  $foundContributions = civicrm_api3('Contribution', 'get', $params)['values'];
-  $contributions = [];
+  $payments = civicrm_api3('Mjwpayment', 'get_payment', $params);
 
-  // If we have a trxn_id check payments for that transaction ID and also return any contributions associated with those payments
-  // An additional array property "payment_trxn_id" will be available containing all found trxn_ids (eg. if you did ['LIKE' => 'test124%'])
-  if (!empty($params['trxn_id'])) {
-    $payments = civicrm_api3('Payment', 'get', $params);
-    if (!empty($payments['count'])) {
-      foreach ($payments['values'] as $paymentID => $paymentValues) {
-        if (empty($contributions[$paymentValues['contribution_id']])) {
-          // Get the details of each additional contribution found via a payment
-          $contributions[$paymentValues['contribution_id']] = CRM_Contribute_BAO_Contribution::getValuesWithMappings(['id' => $paymentValues['contribution_id']]);
-        }
-        $contributions[$paymentValues['contribution_id']]['payment_trxn_id'][] = $paymentValues['trxn_id'];
-      }
-    }
-  }
-
-  foreach ($contributions as $id => $contribution) {
-    $softContribution = CRM_Contribute_BAO_ContributionSoft::getSoftContribution($id, TRUE);
-    $contributions[$id] = array_merge($contributions[$id], $softContribution);
-    // format soft credit for backward compatibility
-    _civicrm_api3_mjwpayment_format_soft_credit($contributions[$id]);
-    _civicrm_api3_mjwpayment_contribution_add_supported_fields($contributions[$id]);
+  if ($payments['count'] > 0) {
+    // We found at least one payment for the params we were given.
+    // We may have more than one payment (eg. A payment + a refund payment)
+    // Return the contribution of the FIRST payment (all found payments SHOULD reference the same contribution)
+    $contributionID = reset($payments['values'])['contribution_id'];
+    $contribution = civicrm_api3('Contribution', 'getsingle', [
+      'id' => $contributionID,
+      'contribution_test' => $params['contribution_test'],
+    ]);
+    $contribution['payments'] = $payments['values'];
   }
-  foreach($foundContributions as $id => $detail) {
-    if (isset($contributions[$id])) {
-      $foundContributions[$id] = $contributions[$id];
+  else {
+    $contributionParams = [
+      'options' => ['limit' => 1, 'sort' => 'id DESC'],
+      'contribution_test' => $params['contribution_test'],
+    ];
+    if (isset($params['order_reference'])) {
+      $contributionParams['trxn_id'][] = $params['order_reference'];
     }
-  }
-  return civicrm_api3_create_success($contributions, $params, 'Contribution', 'get');
-}
-
-/**
- * This function is used to format the soft credit for backward compatibility.
- *
- * As of v4.4 we support multiple soft credit, so now contribution returns array with 'soft_credit' as key
- * but we still return first soft credit as a part of contribution array
- *
- * @param $contribution
- */
-function _civicrm_api3_mjwpayment_format_soft_credit(&$contribution) {
-  if (!empty($contribution['soft_credit'])) {
-    $contribution['soft_credit_to'] = $contribution['soft_credit'][1]['contact_id'];
-    $contribution['soft_credit_id'] = $contribution['soft_credit'][1]['soft_credit_id'];
-  }
-}
-
-/**
- * Support for supported output variables.
- *
- * @param $contribution
- */
-function _civicrm_api3_mjwpayment_contribution_add_supported_fields(&$contribution) {
-  // These are output fields that are supported in our test contract.
-  // Arguably we should also do the same with 'campaign_id' &
-  // 'source' - which are also fields being rendered with unique names.
-  // That seems more consistent with other api where we output the actual field names.
-  $outputAliases = [
-    'contribution_check_number' => 'check_number',
-    'contribution_address_id' => 'address_id',
-    'payment_instrument_id' => 'instrument_id',
-    'contribution_cancel_date' => 'cancel_date',
-  ];
-  foreach ($outputAliases as $returnName => $copyTo) {
-    if (array_key_exists($returnName, $contribution)) {
-      $contribution[$copyTo] = $contribution[$returnName];
+    if (isset($params['trxn_id'])) {
+      $contributionParams['trxn_id'][] = $params['trxn_id'];
     }
+    if (isset($contributionParams['trxn_id'])) {
+      $contributionParams['trxn_id'] = ['IN' => $contributionParams['trxn_id']];
+    }
+    $contribution = civicrm_api3('Contribution', 'getsingle', $contributionParams);
   }
-
+  return civicrm_api3_create_success([$contribution['id'] => $contribution], $params, 'Mjwpayment', 'get_contribution');
 }
 
-
 /**
  * Adjust Metadata for Get action.
  *