You can update your payment details quickly online. Click Here, go to 'Log In' and then select your policy type. Select 'Manage Payment Details' on your Dashboard. You'll be asked for the email address that you used for your policy.
You'll then receive a verification code to proceed so that you can view and amend your card details. If this has not been received within a couple of minutes, please check that the email address you have entered is the one you used on your policy.
You will then be directed to a payment page, where you can update your payment method and submit your new default payment details. Once this has been updated, just sign out to be taken back to your dashboard.