Bait and switch

Began process of moving family plan (6 phones) from AT&T to Xfinity toward end of November.  The then current offer was ($750 credit toward upgrade for each of several iPhone 12 Pro Max’s to iPhone 15Pro Max) 2-for-1 service (unlimited data, total $20 per line for 6 lines) for each line for monthly service, and was set to end December 5.   Agent confirmed that I am locked in for the offer in place at the time we start process of transfer, even though would not complete transfer during the period of that deal.  
I have notes from not fewer than 6 recorded calls, each time with different or contradictory terms regarding pricing information, upgrade and whether I qualify for the offer in place end of November.   Many of the agents initially reported I would not be eligible for the November offer, all but one confirmed I would be eligible by the end of our conversation.  
now that all of my lines are been transferred, Xfinity seems to have decided, and will not budge from the position that I can only qualify for the current offer that is in place, with a sum total of zero opportunity for phone upgrade.

I am extremely dissatisfied with the way. This has turned out and will fight to make it right. The Xfinity customer service line agents and supervisors have no authority to make this right, so I expect that from a formal complaint process.  I do have notes from many of the calls and I know you have accordance. I have the attention and support of the consumer protection  of local CBS Consumer Protection news reporter, and I am exploring options for legal action.   Company needs to listen to the recordings of my conversations with agents. Some I am not proud of, but I have never experienced this level of frustration as a consumer.

Please inform me how I can request an investigation and resolution of my dissatisfaction.