Stole Over $1000 Despite Having Global Travel Pass

I went INTO an Xfinity store two days before traveling to Iceland to have THEM add the GTP to my line for $10 day for 8 days. When my next bill drafted from my account it was over $1000 more than the $80 it should have been. I tried calling their “customer service” which is impossible to reach a human being. I resorted to the chat method where the person on the other end CONFIRMED I DID HAVE ACTIVE GLOBAL TRAVEL PASS for the duration of my trip. But now Xfinity is saying I never activated it. I’ve gone to the local store where they added the pass twice. They’re helpful, but now today they say that corporate denied my claim because it “wasn’t activated”. Which is a LIE since their chat agent confirmed I DID and I have the transcript to prove it. So now what??? They think I’ll just suck it up and let them STEAL a thousand dollars from me??? How do I MYSELF speak to someone at Xfinity who can fix this??? It’s their glitch, their fault! Someone there has a way to refund me my money.