Ignoring Google Home Mini Promo Redemption

When I initially signed up for my Uverse service, I received multiple promotions. Three gift cards which have been fulfilled and a Google home mini which has yet to be redeemed. Promo codes were entered into the system by the representative for all for all four rewards and I have a screen shot of the promo on the date I signed up for service and from what I understand the conversations are recorded. No matter what I do or who I talk to at&t has refused to be helpful by hanging up on me on several occasions and lying to me in saying that they will research the issue and call me back. I'm two months into my service and still have not received my reward. Any one have any suggestions? I'm living up to my end of the deal and feel I have the right to cancel service if the original deal isn't fulfilled.