Unreturned equipment charges

I recently moved and transfered my Comcast account.  When I set up the new address, I specifically asked about the equipment at the old address.  The equipment is installed in a wall behind a panel that I didn't not have access to.  I was assured this was not a problem I had to worry about and Comcast would take care of it.  I moved, set up my new service and everything seemed ok.  Now I'm getting an unreturned equipment charge.  I moved in April.  I no longer have access to the property.  I have made 2 calls and spent almost an hour on the phone trying to resolve this issue.  I was assured tonight that the issue was resolved (something about disconnecting the MAC address from my account) and I would no longer be charged and my account had been credited.  I hung up and checked the Xfinity app and it is still showing a $15 unreturned equipment charge.  Absolutely nothing changed.  PLEASE HELP!!!