After you log into your MalCare account:

Step 1: Go to Account option in the top right-hand corner.

Step 2: From the drop-down menu that appears, select Billing & Invoices

Step 3: It’ll take you to the Account Setting page where should be able to see an option called Change Card. Select that. 

Step 4: In the next, page add details of the new card and Save.

Learn more:  How do I change my current billing address?