You can check the transaction status on the OY! Dashboard to see if the transaction has been marked as “SUCCESS”. If the transaction status on the OY! Dashboard is "SUCCESS," and you still didn't receive the callback, you can resend the callback by clicking the "Send Callback" button under the "Action" column.  

Alternatively, you can also check the transaction status through the API by making an API Check Status request. If you want to resend the callback, you can fill the "send_callback" parameter with "TRUE." An example of the API Check Status for the Payment Link product can be found on the following page. OY! will resend the callback for the transaction if the transaction status is successful from the OY! side.  

However, if your customers have successfully made the payment, but the transaction status is not showing as successful, you can contact our team for further review and assistance.