Error while checking out with xfinity

I received the error 'You’re over the number of lines you can have on device payment plans.' I'm not sure why. I was told by a rep that it was due to credit issues however, I have good credit and seemingly no other problems. Anyone know about this issue or have any input or thoughts? Thanks

Edit- I should mention its for trading in iphone 13pro max for a 16 pro max as well as adding the unlimited data plus. I already have home wifi added