Trade In Disaster

I made the mistake of taking advantage of the Xfinity Mobile Trade in Program. I took up the offer on the "free" iPhone 17 pro on us promotion. I called an agent on the phone to use this offer, and went through the steps of going through the promotion. I thought all was well. After we got off the phone I realized that there was another line added that said "iPhone 17 pro max" showing that I had 2 lines for my plan. Why??? I brush it off, and send my device in and activate my new phone. I went through the prompted steps of activation and transferring my number over. A week goes by and I get an email from Xfinity stating that my trade in was completed and I would have my $1100 trade in credit applied to my monthly statement. I still notice there is 2 lines on my plan so I call xfinity and ask why that is and they simply tell me it is apart of the trade in process. So I continue, the first statement I received charged me for 2 lines and had my device credit. So I was charged for 2 lines when I only use one with ONE PHONE. The next billing cycle I see that my trade in credit is missing. I call to see if I can get this fixed and every agent I talk to is confused on why I have 2 lines, when I can't explain why I have 2 lines myself. And now the agent deactivates the line that has my trade in credit so now I am being told my promotion is nullified!!!!!!!!!! This has been such a hassle to deal with and feels like no one can help me. I learned my lesson on trading in through xfinity. Can someone help me????!!!!!