Ask Smithy Xtra clutchless Commodore

I started to have problems with the clutch in my V6 VE Commodore after 20,000 km. When it started to slip I authorized them to remove the gearbox, but I was warned that it would be at my cost if it was not under warranty. The result was that I was told that it was a worn plate due to my driving style, that there was no manufacturing defect and that it would cost me $3440. I wouldn't care if I had been doing burnouts, track days or drag racing, but I don't, I just use it to drive to and from work on weekdays. Before this I had a HiLux with 220,000 km on the clock and never had an issue with the clutch, so I don't see how it can be my driving style. Where to from here?