The merchant must inform Ratepay of any changes made to an order. The merchant must implement the Payment Changes functionality in their shop backend for cancellations, returns, credits/debits and belatedly added shopping-basket items.
Payment change process flow
Description of Ratepay Gateway operations for post-checkout payment changes:
cancellation
Merchant cancels some or all items of the purchase order.
return
Merchant returns some or all items of the purchase order.
change-order
Merchant or customer adds/removes items to the purchase order.
credit
Merchant adds a credit (discount) or debit (adjustment charge) to the purchase order (after delivery).
In the case of a combined change (e. g. return and credit) the merchant must send two PAYMENT_CHANGE requests, one for the return and one for the credit.