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If you notice excessive condensation on your windscreen and have the panoramic roof there is a good chance the drain is leaking into the car. It turns out it's another shockingly poor design from VAG. It seems they are excellent at high tech, but when it comes to basic stuff they are thicker than a caveman. I mean who connects a pipe INSIDE and connector and not outside !!!!!! doh.
UPDATE 2015: Still dry no more leaks after doing ALL 4 CORNERS, smells or condensation. I have ha a few electrical issues with the RNS and having traced the wires there is some rust on various earth points inside the car cause by the excessive moisture...not much you can do about that other than strip out any wires. SHAME ON VW!!
UPDATE 2016 Car got written off by a 98 year old man who pressed the accelerator rather than the brake and TBoned it!