You can do all of that and more under your Account Settings.
1) To cancel your subscription:
Find Subscriptions under My Account: View your Subscription, you’ll have three buttons across the bottom that read Cancel, Change Payment, and Renew. Note that clicking on the Cancel button cancels your subscription right away, there is no confirmation page. If canceling part-way through your month/year, you’ll have access to the member portal through the end of that billing cycle.
2) To update your payment method:
Make sure you are logged in. On the right-hand side of the My Account Dashboard click Payment Methods. Update card information and enter Save.
For customer support please email [email protected].