repeated problems with front discs?! HELP.

had discs and pads replaced recently, after a couple of weeks Major judder from streering wheel. Found that new pads had scored the discs?! after some argument Audi replaced them under warranty. Its now a month later and am getting judder again?! this time they are not scored just a bit warped, wouldnt mind if iv been hammering around and slamming the breaks on. I heard on other threads that other people have had similar problems with their s3s...do i need to upgrade my front brakes? if so any ideas?