Putting a newer phone (not upgrade or purchased from Xfinity) on phone number that a phone I am still paying Xfinity for

I got a Samsung S22 at Xfinity last May when they had an upgrade special. So, I am tied to the monthly payments and credits and have 14 more to go. It has been a problem phone - I have taken it to the local walk-in repair and they found issues on the motherboard so I sent it to Samsung for repair and have been using my old, old, pre-Xfinity Samsung S6.

But I got a really good deal on an S23 thru Samsung and got it. I called to activate it, wanting to use a new SIM card in case that is part of the problem with the S22, and was told that I would have to set up a new phone line with a new number on the S23 or else I would lose my credits and have to pay the full balance on the S22. He told me then I could swap the phone numbers. So, I did what I was told I had to do.

I worked with them for over 14 hours trying to get the numbers switched. Gave up for a while then finally got someone on the phone that was able to get the existing phone number onto the S23 but couldn't get the new number onto the sim card in the S6 which was fine because I am not using it nor will I be using the S22 except as a backup if anything happens to my newS23 or my husband or daughter's phones. Well, that partially fixed things - I am able to make calls, get calls, and get texts to the original number but when I send a text or reply to a text - it is showing the new line's number.

So, I started thinking and looked at my agreement from when I purchased the S22. It doesn't say anything about having to keep the phone in use, just that the LINE cannot be cancelled which I get and that is not what I am trying to do. Why then do I have to keep this new line and pay $4-5 a month for taxes and regulatory fees? Nothing should trigger me to lose the credits just because I am using a different phone, right?