One year free for adding a line? 50% off a new phone plus $100 GC in the mail... this is what i was promised 0 of this came true.

This summer I was promised one year of Xfinity mobile for adding a new line.  The next year it would be $20.  I was promised that I could buy a new Iphone 16 for 50% off which was about $17 a month. I was told within a month I would receive a gift card in the mail.  I have not received that.  I was told the first bill would be a little bit more however my bill would be about $62 (which includes my original mobile plan of about $40 a month).  This deal sounded too good to be true.  I called after seeing my September bill was over $100, the agent apologized and said he would fix my bill to make it $62.  He was able to do that for me.  He then mentioned I might have to call back in a few weeks and they would have to adjust my October bill.  I've called a few times, I was expecting a call from a manager on Friday however I never received that call.   I am very frustrated, I took notes on my initial call with the agent who helped me set up my plan.   Earlier I spoke to a manage who admitted the agent made a mistake,  these promotions were meant for new customers only.  Overall this mistake ends up costing me almost $480 plus the $100 GC that I never received.  I chatted with an agent earlier and the most they said they could credit me would be $20.   The most frustrating thing with all of this is this is for my daughter.  I know $40 a month difference is not a big deal to Xfinity however I cannot afford the additional $40 and will most likely have to return this phone.  The main reason I got the phone for her is so she could feel safe waiting for the bus by herself.   I've wasted about 4 hours on the phone and chatting with Xfinity and havent gotten anywhere.