mobile phone charges

I had a samsung galaxy S24 phone that the audio quit working on. Took it in to the xfinity store and was told it was defective and couldnt be fixed. Turned in phone for $163 credit but had to finish paying contract on it for 4 months so basically no compensation. was told i could get samsung galaxy s26 at no cost due to promo offer of $899.99 $0 mo. $0 down. Paid $93 at the time ( i am not sure for what) and was told credit of $163 would show on future billings. I believe i was mislead or just plain lied to as now i am being billed for $899 phone for 36 months. WHY?? I have tried to make contact by chat...got cut off. Went back to store...they didnt know who helped me originally and said to contact xfinity.  which i must say trying to contact xfinity customer service is almost impossible as the directions to email make no sense. cant find direct message, new message or pencil and paper???? can someone please help!!!  Account #[Edited: "Personal Information"]