In some situations, it may be in the interest of the receiver of payment to return it partially or fully to the issuer.

Although Pay In DBT (or A2A) Payments don't have a reimbursement option, if you have Unnax's Pay Outs available, you can perform a Pay Out to the issuer as you have the customer, as you have the customer account because it has been informed on the callback event_payin_account_selected.