Iphone 7 promotion not granted

I switched to direct tv because i was promised by an att representative that i can still avail of the promotion even though i already have iphone 7 prior to switching. I've been waiting for 3 months now and still no credit is being applied. When i called them, now they are telling me that i cannot avail of the promotion anymore because i had the iphone already prior to switching. When i explained to them that the only reason i switched to direct tv was to avail of the free iphone, all they say is they cannot help me. I was giventhe information by their customer representative and they cannot do anything about it because there is no written documentation provided. I've been with att for a long time now and trusted their words over the phone and now they are telling me that i cannot trust what i'm being told. This is very frustrating! One of the managers i talked to even yelled at me for waiting on me to provide the account number. I've never had this terrible experience with att. I hope somebody from the corporate department reads this and be able to help. I would have cancelled both att and direct tv right away if only i dont have to pay the cancellation fee,that's how frustrated i am. If they cant give me what they promised, i hope they let me cancel my accounts without charging for early termination fee.