If you are checking out and you enter incorrect information, the system will display a message that the transaction has been declined. You can usually enter the correct information and resubmit it for payment.
If you are using the correct card information but the transaction is still declined, there may be a mismatch between the billing address entered and the address your bank has on file.
To change the billing address, a new order must be submitted, you cannot change the billing address once the payment process has started.