Xfinity sent me to collections in ERROR

I got a phone Dec 2023 & returned it January 4 2024, they credited me everything back except $16.70 for an activation fee. Which was in error since i never even removed the phone from the packaging. I spoke to someone last Monday 5/20 & noticed, only because I was trying to get new service. They recognized the error and credited the account, however now my rep-out is jacked because the $16 sat there unpaid for an entire year! so when i go to get mobile service it only gives the option to BYOD or buy in full, when initially i had a $1k limit! I keep getting the run around, being told to reach out to credit companies(i called they said they do not have my debt), the amount credited is also different than the amount listed on my credit report so I don’t even have strong enough proof to dispute! Now I am not only without mobile services but I also have an error on my credit report. I asked Xfinity why is there no assistance when trying to get this resolved even though it’s no fault of my own & the gentleman told me simply because there is nothing they can do. Imagine calling a reputable company for an error they made on your name and they say there’s nothing they can do??? What the heck!