The payment system where you purchase credits with your credit card has had problems since introduction, with many soon after not able to spend their credit, getting the same error.
The only chance for support on your account is to use the official help assistant linked above; this forum is just fellow users.
Confusingly, this is also the error that someone would get if they hit their own hard limit setting or monthly usage limit (which still exists), or had never input a payment method.