My Audi TT, 1.8 (180bhp) Cabriolet;

Returned home from traveling after 2 months. My car was left on my driveway, so has been left exposed to all recent weather in the south East of the UK. nothing out of the ordinary i'm sure you'll all agree.
1st time i stepped into it... i smelt the mould. All the Carpets are DAmp through.. the underneath of the roof was damp too. Mould had appeared on the headrests, and on the seatbelts.

I have look extensively at the possibility of the roof maybe having a hole in it. but it doesn't....... I can only imagine that there is a water seal broken. Failing that i can only imagine that my windows were left open.. (Impossible)

PLEASE PLEASE PLEASE - If you have encountered anything like this, let me know... If the seals on these go after a few years, then it might be time for a new roof.. I REALLY DON'T KNOW!!!

Any help/advice would be greatly appreciated!!