There are several reasons why a credit card payment can be refused :
-The credit card used must be either Visa, MasterCard or American Express.
- Wrong number, expiry date or CVC, mispelled name...
- Not enough credits on the card.
Depending on your card, you can be redirected to your bank website to confirm the payment.
Usually, a password or similar must be entered to ensure that you are the rightful owner of the card.
Failing to do so, can lead to payment refusal.
Any problems in this step should be dealt with your bank directly;
For more information about payment methods refer to "Which payment methods do you support?" article.