If a problem arises in terms of ordering your order, try to validate your order from another browser (Internet Explorer, Safari, Firefox, Google Chrome, Mozilla) or try to go to a computer if you are on a tablet or a smartphone .
If the problem persists, change the means of payment (visa card, paypal), (note that it is possible to pay with your CB on Paypal, without having a paypal account)
Or get closer to your bank to get more information.