Verizon Final Bill

I switched phone carriers from Verizon to Xfinity Mobile about a month and a half ago. I was told by an Xfinity service representative that once I switch over to Xfinity Mobile, everything will be taken care of, including “all charges incurred during my time with Verizon”. After everything had been sorted out, I had tried to log back into my Verizon account to see if there was any last payments I had to make. Little did I know, that when I had switched to Xfinity Mobile, there would be no way for me to access my old Verizon carrier account. So therefore, I wasn’t able to see any remaining bills I had to pay with Verizon. After hearing that Xfinity Mobile uses Verizon’s cellular network data, I assumed that maybe, my incurred bills from Verizon will transfer to my Xfinity Mobile account. That was not the case. After paying my first billing cycle with Xfinity, I get an email from Verizon stating that, I still owe a “Final Bill” amount of $540.87. There was little to no explanation about how to get a reimbursement for any incurred bills I had while I was with Verizon. I feel like I got scammed.