Unfortunately, it is not possible to change a payment method after completing the order.

If the order is not completed with a payment, it is automatically cancelled. You would then have to place a new order.

Was your order cancelled when you reached the payment stage? Did you see an error message saying your payment was blocked?

Sometimes some computer security software blocks payments incorrectly. If your payment is blocked, you can try temporarily disabling your security software. You can also try placing the order using a different payment method, a different browser (our experience is that Google Chrome works best) or try again from a different computer/IP address.