Problem with wc-api call from a bank for custom payment gateway

Hi, I need help with setting up the recurring with my custom payment gateway. I successfully started a recurring by providing required parameters to bank. But once the child payment process happens at bank end it doesn’t update the order subscription on my WordPress website. I have setup the API call https://www.example.com/?wc-api=wc_cardlink but it doesn’t work. However i tried to call it with a test form and provides an order id to that call so it updates that order subscription but when bank calls it doesn’t work. Please help me sorting out the issue. Any help will be appreciated

Thanks