Renault triber

Bought a renault triber amt. From brand new complained about the gearbox return it the next day but refused to take it back now they have to replace the clutch plate it costs about 26000 to replace i sent 50 emails about the gearbox to the dealership and to renault SA but do not want to help the car has to much problem the clutch plate should be covered by the warranty because the problem is the gearbox not happy with renault triber