Chances are that it will be the common problem of the vents behind the rear bumper leaking. Upgraded ones are apparently available and are cheap, but you can apparently reseal the existing ones. There is a How To on removing the bumper on here somewhere.
I looked at someone documenting this job on the forum only a week or two ago. Even with the new vents, they silicon sealed them in to make sure, which is what should happen from the factory to avoid this.
Edit: Gazwould, just seen your post.
Hardly environmentally decision making from Merc there given the resource that then has to go back in to correct the job. Possibly repeatedly. With more new parts.
Chances are that it will be the common problem of the vents behind the rear bumper leaking. Upgraded ones are apparently available and are cheap, but you can apparently reseal the existing ones. There is a How To on removing the bumper on here somewhere.
Hi, i had a c200 early last year and had this problem"a lot of water in rear footwell" the garage i purchased the car from "tried" to fix the problem,which they said water was coming on through top of windscreen which was a badly fitted replacement,i was not happy at all with repair so i returned car with a full refund