BMW of South Atlanta

I ordered a 2008 X5 in Nov 07 and in Jan of 2009 the differential went bad and I was told they were unable to repair the vehicle. I then purchased a 2009 328i coupe and was told by the Finance Manager stated, agreed and signed the Extended Maintenance Warranty and the Tire Warranty. In March 2011, the regular standard warranty ran out and the dealership refuses to honor the executed agreements that we signed. Their response to my complaint is that they "gave me a new vehicle" so they don't owe me anything. This is literally the worst service that I have ever experienced. A lot of money has been paid for both vehicle so it is sad to see that a reputable dealership would do behave so horribly.