Been trying to setup cellular on an Apple watch for a year

Hello,

I have an Apple watch that I want to setup for my child with cellular service.  I've been attempting to get this to work for a year, via chat, phone calls and in person at Xfinity stores.  I won't go into the full history, but just tell you where it is now.  I setup the watch for my son, it pairs successfully to the iPhone, but when I try to setup cellular it tells me it can't because the watch is currently activated and paired with another phone.

They were unable to help me in the store and said I need to call in to get the watch switched to be a standalone, but I've gotten better support on these forums, so I'm trying here instead. 

Also note I've been paying for a line of service and a watch that was supposed to be free for a year that I've been unable to use.  The store created an incident to help get me a credit for that as well.

Is there anyone who can help me?