Promotion gift card

In March I switched my phone over to att. During that time there was a promo where if you were a new customer, and ported your number over with you, you would get a $250 dollar gift card after 60 days. 60 days past and no gift card email or whatever. I spoke with multiple employees on the online chat, all saying I would get it. I have screenshots for proof. One employee said it was being mailed to me and on the way. This was after I had cancelled my service as well. I cancelled on May 2nd because 70 dollars a month for bad service is not something I’m going to pay. Last night someone I talked to said that there was no promo during that time. Why would I lie about that? This is absolutely ridiculous. I cannot believe a company would treat a customer like this. I will NEVER come back to att nor will I recommend them. They call their customers liars, and lie to them. I just want the gift card I was promised. This is insane.