cancelling service for closed location

We have the Activecore/SD-WAN services across the six locations (Now 5) of our company. One of our locations has closed down and ceased operations as of Sept 30th, of 2022. We have notified Comcast of this numerous times. We have filled out the forms they have sent us and returned the equipment, however we are still being billed for this location. To be perfectly honest, I am tired of dialing customer support over this same issue. How do we find a point of escalation over the retention department because this has gone far beyond ridiculous. I don't want to talk to another helpdesk because we have been going back and forth with this and each time they tell us that things are okay, the next month we get a bill for that location. I'll say this again. The equipment has been returned. We know because they have verified the equipment has been returned. 

I am looking for a way of reaching senior management over this issue and not talking to another telephone representative who can't do anything but tell us the same thing over and over again.