Xfinity system will not upgrade phone

I have 3 iPhones on 3 lines. I want to upgrade the older phones to newer ones. One replaced fine. The other 2 would not proceed in the system to replace, I.e. the system screen has a greyed out button that does not allow the tech to complete the process. A problem ticket was created and it has been two weeks without resolution. Should I just go to another carrier and drop Xfinity after 36 years as a customer?