I was promised a $150 gift card

When I signed up for u verse I was told if I add home phone service to my Internet that it would be the same price as the Internet only for 1 year. I was told instead of a $50 gift card I would receive a $150 gift card. That's the only reason I got the home phone service. I don't even have a land line phone. The guy on the phone talked me into it for the extra gift card money. Anyway when I checked my rewards it's only showing a 50 gift card. I need answers! Thanks.