Misleading xfinity mobile service/internet promotion

In March, 2023, I was offered a promotion to get $30 off my internet bill per month for twenty four months if I switched to xfinity mobile. I did, and when i got notice for my April bill- it was for the regular amount-i didn’t get the $30 off. I called and was given a credit of $30 and was told the customer service agent would fix it so I didn’t have to call again. Happened again in May, so clearly it wasn’t fixed. Called again and was told the same thing. Third time was June. Happened again, but the customer service agent told me he couldn’t give the the credit but that he would get it fixed so it would automatically happen for that month and from then on. He said he would call back. He never did. After spending hours on the phone (with on hold and being transferred back and forth between xfinity internet and xfinity mobile and/or being disconnected in the process of being transferred), I got sick of calling and figured I would wait a few months so I didn’t have to call every month. I called when I got the September notice, and again another round of being transferred /on hold/disconnected ensued. Finally someone came on the line who said I was told when I signed up that I would have to make a chance in my internet and get xfinity mobile in ordered to be considered for the promotion. I patiently explained that not only was I not told that, but out of every other customer agent I had spoken to, not a single one said that I would have had to do that. That this was the first time I had ever heard that. She stuck to her guns and said there was nothing further that she would do. I have never had such bad customer service in dealing with any other communications company. After leaving a poor review of the interaction (really- you want me to take a survey after that?), someone from the corporate office emailed me to say he would like to discuss what happened and could I respond with a good time to talk. I did, and guess what- didn’t hear another word. So fed up- if I didn’t need to use the internet- I would be long gone from xfinity. Unfortunately, they’ve got a monopoly on my area so I can’t do anything at this time.