Fitzgerald Gaithersburg Hyundai

I bought a 2008 Hyundai Elantra GLS automatic with popular equipment package from this dealer for $13911 including $1500 rebate. At the time they guaranteed me that I would not find a better price anywhere else or they would refund me 100% of the difference plus give me 50% of the difference in parts and service. Well, two days later I found two dealers who beat their price by at least $300. I drove in and spoke with the general manager and showed him verifiable proof that two other dealers beat his price on the exact same car, but he would not honor the guarantee unless I brought in a signed purchase order. I tried to plea with him that there is no way any dealership is going to give me one, especially since I had already bought the car (and he knows it too), so there is really no way for a customer to make them honor their guarantee. In short, I'm happy with the car, but I feel like I was taken advantage of because they are refusing to honor the guarantee that I was given when I signed the purchase contract.