Often times users will need to update/change the card that is on file with their account. This can be necessary for several reasons including failed payments, expired card, or the user now just has a different card.
Updating the payment method is easy and is done in your workspace settings under "Plan and Payment". (To get to the settings page click the settings gear located right next to Find a Time on the main scheduling screen). As you can see in the screenshot below once you are in the Plan and Payment section you can select to "Add a Payment Method". Once that is done you can click "Change" under the primary payment method and change it to the new card you added.