Well it sounds like you had reported the problem before the Flywheel/Clutch installation. That is enough evidence that the problem originated before the addition of the aftermarket product. You are going to have to fight it but you can get a tranny from them on warranty. I had tranny problems on my previous Z also. I ended up having to hire a lawyer but it all worked out. It looks like you are in Mexico.........I dont know how the laws arfe there but I suggest you push maybe consider a lawyer.