If you pay annually you will not be able to change your payment card online until your next renewal.
You can switch the card your monthly instalments come out of, as long as it’s to another Visa or MasterCard credit or debit card.
To do this simply login to Manage your policy. Once in the policy summary page, select ‘View and Update My Policy’ - here's an example below.
This takes you to the policy summary page shown below.
Click on 'Update my policy'.
This brings you to the Update my policy screen shown below.
From here, click on Payment details.
This brings you to the screen below which shows your current credit or debit card details.
Click on Update payment details.
And you come to the screen shown below, where you enter the new credit or debit card details, and then click on Submit.
Which brings you to this final screen to confirm that the new card has been updated.