If your Common App payment failed, you should first contact your bank to inform them about the international payment to Flywire. This may resolve any restrictions or filters preventing the payment. You can then reattempt your payment using the Flywire tracking link sent to the payer email to re-enter your payment details.
If you have already cancelled a previous payment request and need to make a new one, return to Common App's website, resubmit your application and click the "Reattempt payment" button. If this button is not visible, contact Common App directly with the subject line "International Payment Status", your Common App ID (CAID) and the name of the institution you are applying to.