Payment getting rejected

Hello,

This has been happening to me all day. I'm paying with a CIBC Visa creditcard and my other Mastercard. Neither are working. It just tells me payment rejected with no explanation. I called my bank and they haven't picked up a transaction that they rejected so it definitely can't be on their end. I even tried getting a friend to pay on their card and it didn't do anything.

Anyone know what could be happening?