Xfinity Messed up My Internet Account

A rogue agent at xFinity signed me up for 2 mobile phone lines which I did NOT order.  They have since removed the mobile account but they have not removed the credit  card on auto payment connected to that account.  I can't remove this credit card myself because it would not let me, because I got an error message saying that the card "is still connected to the mobile account," which is non-existent.  It's been almost 4 months that I've been in contact with their support agents at supposedly typical level and corporate level through multiple calls and text messages, but they have not been able to complete a simple request of removing that credit card.  I had this auto payment for the mobile account blocked, but now I've been getting email messages in the last couple of months to update my credit card information because the charges that xFinity attempts to make has been declined.  On top of that they're, out of the blue, charging me  almost $40 for the xFinity Flex box, supposed to be free with the internet service, and NOT working for months.   Well, I'm going to return the box and I'll be looking for a different internet service after the current contract is over.  I'd bet that the credit card on auto-pay would still be in their system.   I'm done with chatting or talking to these agents, because nothing has gotten resolved! 

I'd bet you that they'd remove this post after I ignore their trying to have me direct message them to get the problem resolved.  What's the point to my doing that when several months of wasting my time.