Xfinity Mobile Trade In and Assurant Unable to get any answers.

I returned a phone for a trade in back on 06.07.2024. I have emails updating along the way saying "your device is on its way to us", "we recieved your device", and "we have reviewed your device and it has been approved".

Now, weeks later I have a charge for the full price of the iphone 14pro max that I returned and was told it was accepted (the phone was in like new condition). After the abismal A.I. that xfinity uses to call support I finally got ahold of a person to talk to and was told that it could take up to 30 days for charges to be removed and that it would be removed by 07.07.2024. Today 07.08.2024 I once again spent 15 minutes calling in to get ahold of an xfinity agent (keep in mind even if you call the posted xfinity mobile number it will connect you to the normal billing department then they have to transfer you specifically to the mobile billing department). And they told me this was an assurance issue and that they needed to confirm it was recieved.

They then gave me the number to assurant and it is not actually possible to get someone on the phone. I talked to a support agent online who is now saying this is a xfinity billing issue, it is an endless cycle of automated calls, not being able to speak with someone, and nobody being able to remove this charge from my account. I mailed the device back and have confirmation that it was recieved and approved. Can nobody remove this charge from my account? Wether you have the device in your warehouse or not, I don't see how I am being held liable for someone on your end misplacing or mislabeling a device. I cannot even pay my mobile bill because I am not paying an additional ~$500 for a charge that shouldnt even be there. As of now xfinity and assurant are pointing fingers at eachother and there is literally nobody who can assist me. Either someone on support needs to assist in removing this charge, or apparently my services will just eventually cancel because of a missed payment?