Is this the original kit from 2005? Unless you or someone else changed the clutch on a like for like basis, or abused it for it to wear early, I can't see how it's the fault of LUK. We do a lot of their kits at work & never have any comebacks. I had the clutch done in my sisters Golf over xmas, symptoms were it felt like a misfire at idle, lumpy, but it ran fine. It turned out the DMF had gone out of balance. New LUK kit was fitted & it's been spot on.
How old is the kit?