Issue with mobile phone bill

I signed up with Xfinity 2 months ago. The mobile phone line was free for the first year. I just received a phone bill. This is included with the plan I’m on. I have spent 50 hours talking to people at Xfinity, all to no avail. They also have 2 mobile devices on my account. I only have one. I have never had two. The person I spoke with assured me they removed one of the devices. Of course they didn’t.

most incompetent customer service I have ever come across. I’m at a loss as to what to do. Probably mediation or small claims court. 
I know Xfinity doesn’t think their customers time is valuable, it is. It’s pointless to call customer service any longer. They can’t resolve the issue.