HELP!!!! Clutch issue

I have the 2007 Shelby gt500 with less than 20000 on it and 1st and 2nd gears are fine but when i go into 3-6 and push a little harder the RPMs rise . I was told by my ford dealer that the clutch warrenty is 12/12,000 miles. I very seldom drive the car hard. has anyone else had this problem with the clutch starting to go bad at early stage. They also told me it would be 700-800 range to replace it. he told me that everything else has warrenty except the clutch. something doesnt sound right!

PLEASE help me!!!!!!