Escalation needed

I purchased an Apple Watch from Xfinity.  It has cellular ability, which is why I got it… however, when I try to activate the line on Xfinity.  It fails everytime and customer service has been awful. They seem unknowledgeable, irritated, and happy to run the clock without finding a solution.  I’m exhausted and deeply regret this purchase.  Please please please connect me with someone who is knowledgeable.  I’m trying to do exactly what Xfinity wants (buying from them and adding a cell line), and it isn’t working.  This shouldn’t be so difficult to solve.  BBB is my next call.