Xfinity Mobile is scamming

Xfinity gave me a non working phone and I returned it within the warranty return period and received a new iPhone. I called and made sure they had the returned phone and they said that they received it. A month or so  after,  I was getting a charge on my account of $729, I called immediately and asked why my account is being charged $729 and the representative said that it had been a mistake and I shoud restart my Xfinity app. The charge then went away.   I asked if they are charging me for the phone and they said no they received the phone. I called again a few weeks after because the charge posted again and they said that I should not worry this is a mistake, we received your phone. Now, March 29 2025 I have been charged $1300 to my account and my phone line was disconnected. I was told I needed to pay the balance in order to receive service and I asked why am I paying $1300 for a phone that I am monthly for and they replied it must be a system error we will get this to our higher ups to address the issue. I never heard from the higher ups and I gave them 4 days to call me with the call back number I provided, never received a call. I called and they said that they are still working on the issue call back in 48 hours if no response, I received no response after giving them 5 days. I called again and then they said that theyll just investigate and file a claim for a credit to my account this will take up to 48 hours. It is now April 13, 2025 and I am still without service and now they are claiming they received it after the 14 day warranty AND blaming me for damaging the phone first phone sent.  I am lost for words because I have proof of returning the phone before the warranty exchange and I returned the phone undamaged. So I'm literally being scammed from the company due to their mistake of sending me a non working phone the first time. And I just can't believe they told me this whole time that they received the money before the warranty exchange but now all of a sudden they did not after months of me having this service. They never addressed the $729 charge either. This is a scam and I do not deserve this, especially since I am on top of my bills and paying early.