Without reading the whole thread, I've had an 09 A3 from new and now I've got a new MK6 GTI. They've both been pretty crap to be honest. So far the GTI's had a new water pump (after 300 miles), gv gaiters greased, wind noise fix, wastegate rattle fix, bonnet/bumper realigned, new clutch, new slave cyl, and probably some other stuff. It's on 4,300 miles now, less than 4 months old. Most of that mileage is to the dealers and back 
A3 has numerous things incl sensors, water pump, heater, horn etc etc can't really remember everything.
Funnily enough I had a Corsa before these and in 2 years it went in for an ABS recall and that's it............. 
WTF

Indeed!
The water pump started making a really loud high pitched noise, it took a few attempts to get the dealership to replicate the problem. Eventually they did and replaced the pump. It came back after a few weeks but then disappeared and so far, touch wood, it's not come back again. Seems to be a massive problem on US spec GTI's from looking at different forums.
CV, wind noise, wastegate rattle, poor bonnet/bumper alignment - just down to poor design or workmanship. All seem to be a common problem
The car was mapped and I was getting some epic clutch slip

Fortunately I managed to convince the dealership that the slave was leaking (just a guess) and it actually was, so they stripped the gearbox and replaced the slave. Also as it had been slipping, the clutch was worn, so they replaced it too, despite the fact they know it's mapped so can't really complain too much.
I've had good service by the dealership but I will certainly consider not going VAG next time