My car went in for a couple of niggles on Weds, inlcuding a wet drivers window (not much of it) and straight away the technician told me it was a known fault without a cure. Interesting reading your comments, guy - pity Nidd is so far...
Go straight back to them and print this off/ point to this thread and tell them there is a cure and to contact seat technical directly for advice on the fix!