To change your Credit Card/Debit Card information, you will need to log into your account at www.btwb.com. Once logged in, click on your personal drop-down menu in the top-right corner of the header, then again on "Subscription".
Your Subscription page will display all active subscriptions. Select "Manage" next to a subscription to edit your current credit card on file.
You will then be able to manage your card inof. You can set your default card, add a new card along with other updates your your subscription.