If you're having trouble changing your card details, follow these steps for an alternative way to pay.
Go through the checkout process as usual as far as the Payment screen. Before confirming your payment, click Use a new card (as shown below) and it should allow you to enter new card details.
Finally, select Confirm & Pay to finalise your order.
Alternatively, you can select PayPal as the payment method and click the yellow PayPal button (as shown below).
You will be taken to a PayPal login screen; simply click Pay with Debit or Credit Card and you will be able to pay with your credit/debit card without having to set up a PayPal account.
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