They won't credit my trade in

I have switched services to xfinity since 2025 and I had nothing but issues. I ended up getting 2 more lines back on sep/2025 and I trade in 2 phones I received the trade email confirmation and now they are telling em I owe them and that I need to pay them and I got hit with a 2700dl bill and my lines are now disconnected. I have called and been in the phone for more than 7 hours at the time and I keep getting told I need to pay