Unable to get remainder of rewards promised - DirecTV

Was promised $350 in rewards if I switched to Directv from Dish to lower overall Uverse bill. I told agent that I had a contract with Dish And buyout would be over $400. He said he could not do $400 but he could do $50 of next bill, which I received, and $300 in rewards cards. So far only have received $100 card and been given the runaround about the last $200. I would never would have agreed to the two year contract with Directv if I had know I would have been cheated out of the promised rewards. I did have to pay Dish over $400 dollars to break the contract. I have been an AT&t customer since 1969 and I got Dish TV when AT&t was offering their services.