I am having problem with my passenger side light. Bulb was changed and I can't see when lights are dim. It looks like a drape is over light. I have taken car in 4 times, and I have to take back again. They acknowlege problem but do not know how to fix. I feel service guy messed up something when he changed bulb the first time.
I was having the same issue w/my 09 C300. I found that I have not seated the bulb properly and it was sitting in the socket at a slight angle. Once I seated them, my low beams efficiency improved dramatically. Hope this helps