My warped world

I HAVE had problems with warped discs on the Mazda 6. At the 30,000km service, I complained that the front brakes had a shimmy when applied at speed. As a result, new discs and pads were fitted. I also told the dealer the build-up of brake-pad dust on the front wheels was abnormal. Since the new discs have been installed there has been no dust, which leads me to believe the warped discs were installed during manufacture in March last year.