Unable to upgrade phone with monthly payments

We have had our Xfinity mobile service for 2 years. Never had a late payment and have paid off our phones. We paid for our phones on a monthly payment plan. Our account says ELIGIBLE for an upgrade however when we went to get a new phone today we were told we had to pay in full. We were told the reason is because we no longer have internet services through Xfinity. We cannot have Xfinity internet due to it violating our contract with our apartments internet provider. When we turned off our internet we were told by 3 people it would in NO WAY affect our mobile service or its terms. I asked about the upgrade terms and was told that as long as payments were paid on time and the device was paid off we would be eligible for the same financing terms. We are confused and frustrated and would like this rectified. PLEASE stand behind your loyal customers and provide them with the same terms as when they signed up for you mobile services. To be completely honest.. why would we want to continue service when we are treated so horribly?