Originally Posted by
usually sat at the back
The online system does prevent you from paying off more than the balance
Yes, just tried it for a credit card via the Amex website and got:
The amount you attempted to pay exceeds the Total Balance on your account.Please reenter a payment amount that does not exceed this value.
However, As
BlackBerryAddict said, the OP may be able to transfer direct from a bank account to the credit card.