Is the warranty in writing? What are the terms? Is the problem covered by the warranty? Have you had the problem diagnosed? I always suggest getting a mechanic other than the dealer to diagnose the problem then demand the repairs be made under the terms of the warranty.
The smartest car sales fraud lawyer in Georgia is Mike Flinn in Atlanta. If the dealer won't take care of this for you, and you think that are supposed to, then call Mike. He can tell you what your rights are and what needs to be done.
This answer is for general purposes only and does not establish an attorney-client relationship. The law in your state may differ and your best answer will always come from a local attorney that you meet with privately. For a Free Online 50 State National List of Consumer Law Lawyers, click on this link (http://tinyurl.com/79ku5jx) and find one near you