You can log in to your account here. Under the section ‘Your Payments’, please select ‘Add a new card’ and enter your new card details as required. Please look for the ‘Add card to existing order’ tick box if you need to assign this card as your default payment option.
Please ensure your address is also up to date. Once you’ve updated your payment card details, you can then pay individual instalments, make one-off payments, or clear your balance.