SLK (2004) Brake light problems

[sarah]

First one brake light was out, so I got a new bulb and it didn't work, so I took it to Mercedes and they said it was "probably" the bulb holder had melted and it was a known design fault, they also said the other one was likely to go too so I may as well get that done too, for which they were going to charge me £280!!!!!!!!!
They said the whole of the back lights would need changing!
So now the other one has gone too.
Anyway I took it to a mechanic who said it may be a pedal switch (but the boot light still works?), or just a connection, and I've seen people on forums say to put a bit of plastic under the bulb holder to force the connection.
Does anyone know about this??? As there are 3 parts involved here, the bulb, the metal bulb holder that in turn fits into the housing. Do I put it between the bulb holder and the housing?
My poor pretty car is not happy with no brake lights!
Any advice much appreciated