To pay for your order you can use any of valid Visa, MasterCard, Visa Electron and Maestro cards. If your payment is declined, you need to place your order again. Also you should check are you doing correct steps to process your payment. Check your card details, e.g.: expiry date, security code or your name. If you still cannot make your payment, you should check the reason with your card issuer and make sure you have sufficient funds. Alternatively, you can try to make a purchase with different card.