Need help disconnecting service after move

On August 21 I called Comcast requesting a move from my old office to the new one, in the same building.  Comcast sent me documents saying the requested install date was 8/24 and the requested disconnect date was 8/26.  I moved to my new office 9/1.

After multiple frustrating phone calls, the tecnhicians finally came to move my service on 9/21.  The technicians tried very hard, but ultimately determined my new office was unserviceable.  Meanwhile, I am still being billed for service in my old office.

When I called and attempted to have Comcast stop billing me for service at my old address, I was told I would have to pay an early termination fee for "cancelling" my service.  I can't seem to make anyone understand that I didn't cancel Comcast - Comcast cancelled me.  

I've asked the reps to have a supervisor call me, but I'm not the least bit surprised that they haven't.  I would like to get this resolved without resorting to further action.