unlock sim

I initiated a line transfer to Verizon and purchased a new iPhone 17 from them. Their instructions stated that once I received the new phone, it would connect with their servers and complete the transfer request.  As soon as I turned on the phone, it connected to Xfinity and locked the sim.  I have chatted withthe  Xfinity assistant many times now and have been told each time that the IMEI I provide them is not on my account and only the Iphone 15 is showing as an active line.  I was able to turn on the iPhone 15 (thankfully, I hadn't sold it yet) and get it to connect to Verizon and complete the port.  However, when I try to enter my IMEI for the iPhone 17 I get a message that it is locked to Xfinity.  I have now completely cancelled my Xfinity account, but the SIM is still showing locked.  I was provided a phone number to call for customer service, but each time I call, I either get stuck at a prompt that won't go anywhere, get met with complete silence, or get told that I can use text messaging, which fails as soon as the call disconnects.  

This IMEI should never have been activated on Xfinity and most certainly shouldn't have locked to the carrier.