as has been said already, passenger side i would say its the battery tray, drivers side would be the fuse box. On my mates S1 the water was leaking in through the panel seam, along the bulk head, the seam sealer can go a bit manky there.

Also worth a look would be to see if its coming through the screen rubber, especially if the valet used a high pressure water jet, it could be that under the rubber was a load of built up gunk that has now been cleared away its got nothing to seal it.

Another place would be where the motor for the heaters is, the black surround might not be sealing properly, causing water to leak under.

Was it wet at all before the valet?? could just be that its creeped in from that.

The only 100% way to see where its coming in from, is to take out the carpet, and soundproofing. And take out the dash. Then get a mate to use a hose pipe or watering can, pour water over the car/area you think its coming in from, whilst you sit in the car and look for the water.

Hope its not anything too major, from the sound of the car as you have described it and from the pics on the other thread i would say it probably isnt a bodywork problem. As yours looks

And thats the cars body work not yours


lol