Mazda will not honor warranty even the car is in warranty.

I bought RX 8 in 2004 with 17,000 miles and till now car went at least 3 times for gear problem. I still have warranty of 15,000 miles left and have gear problem and they refuse to fix it for no good reasons, they are saying it is my duty get it

fix and I cannot understand how it is my duty to fix, can somebody can explain ? Not only that I had taken for grinding noise from 4th gear and they refuse to fix it so I ask my car back and when I got my car back I discover my 6th gear is not working and Ramsey Mazda says they did not do anything to my car, which I doubt otherwise why they kept my car 10 days.Every time I called to pick up my car they said it was not ready now they say did not do anything to my car.

Please do the justice.