May not be relevant, but we had an A6 not so long ago - the comfort module was wet and giving us funny symptoms.
Sure enough, under the carpet was soaked - took about 10l of water out. Carpet was dry, but you could hear the water sloshing!
On the A6, it was under the carpet where the passengers feet would be. Black box about the size of an A5 sheet of paper and an inch thick.
We took ours out of its plastic casing (full of water too!) and cleaned all the circuit board with a toothbrush and contact cleaner and left it in the airing cupboard overnight to dry properly.
Lucky enough, that sorted all our issues. Hopefully yours will be as easy as that.