We appreciate you for using the Xfinity Forum to report the issues you're having when attempting to update your payment methods. My team can investigate and may also be able to add the cards here on our end. If you @Cfowler4774, if you haven't already, can you send a private message? To send a private message, click on my name, "ComcastChe," and then click send a message. Please include your first and last name and address.
@gsimmonds, I'll be replying to your private message shortly.