Account disconnected due to xfinity mobile error

Xfi ty mobile offered a trade in 2025 to update iPhone 16. If I was to trade it in I would get 750 off the cost of the phone and if not I would pay the full price of the phone. I clearly was financing. Since I did not return my iPhone 13, which was til Jan 2026, they charged my account 794.00 but as a lump sum. I was told since Jan 2026 til May 2026 that it was going to be corrected. On May 14th they attempted to charge my account 1300 when my monthly payment was 180 and disconnected my account and sent it to collections on my due date. This charge was supposed be absorbed in my financing as the did my daughter iPhone 16 in Jan 2025. I work for uber full time and have not been able to work for 14 days as it requires my phone. This is an example of what should have happened