bets wya to check for warped discs is to use a 'clock' as the disc is being turned, you will then be able to see any variation of the surface that would cause vibration (there is a tolerance level, anything above this wouldnt be good) it is highly unlikely that you have had 3 sets of duff discs, i could understand one cheap set, but not 2, and then for genuine vw discs the same no way. when alot of garages are busy they forget to do simple jobs like clean up the hubs with a wire bush etc, not cleaning the calipers and re greasing any sliders etc, these need to be done for your brakes to fit and work perfectly, if not done crap on the hubs can give a 'juddery' sensation similar to that of warped discs but i would have thought it would have been near enough instant rather than 2 weeks down the line. also get wheels rebalanced as sugar described just to help eliminate any wheel wobble from the problem, id get your abs checked to, as a fault on this which may not show on your abs light on dash etc may be causing then to do what there spose to do when skidding, this could cause a juddery effect too.
