Apple Watch double charge/Terrible customer service

I had purchased Apple Watch from Xfinity for my son. I had purchased using Xfinity Rewards. For the activation I spent 4 hours on calls with different customer service associates to transfer an existing number to the Apple Watch as a standalone device. In the process, Xfinity dropped the promotion. My monthly bill shows two Apple Watches and I am being charged for device payments. I have already spent two hours with customer service. It has been 10 days until now, the issue is not resolved. When I call it gets transferred from one agent to another agent four times around the globe. 
It is very frustrating. Never seen such a terrible customer service.