There are a number of reasons why your payment may have been declined. Make sure:
to enter the correct card number, CCV, and expiration date;
that your card has online transactions enabled;
that you have sufficient funds in your account;
and that your card has 3D Secure activated.
You can also try using a different card — you don’t have to pay for your booking with the same card you plan to use at pick-up.
If you're unable to determine the reason your payment was declined or the problem persists, it’s best to contact your bank for more information.