In 2001 my father imported a S320 CDI from Austria.
Afer a year or so, the passenger window started going up and down of it's own accord. He was on holiday at the time, so called in to a nearby Mercedes dealership in Cornwall, who disconnected the relay or something, so that he could continue without the window open! He left it like that for a while, and then decided he should do something about it. So he visited his local Merc specialist (but not a main dealer) who said it was his black box (presumably ECU?) and so a new box was duly installed and hey presto - problem fixed. For a day. He took it back to them, they scratched their heads, and decided to leave it unplugged again.
A few months later, he was over in Austria again, and had become annoyed at having to open the passenger door to pay the tolls rather than open the window, so took it back to the main dealership where he oringinally purchased the car. They looked at it and declared that the 'black box' was faulty... so he had it replaced again. Guess what... as he hit the shores of the UK, the window decided that it would like to let some fresh air in...
Understandably, he's reluctant to spend a third £350 + for a box only for it not to work...
The car also does something else odd. The drivers door will start clicking, as if it's trying to lock the door, and the courtesy lights come on in the door, even though its shut. This is agian, intermittent, and easier to live with than a haunted window.

So.. what I'm looking for is advice. What should he do?

It seems to me that perhaps the black box is the symptop not the cause - ie something else is 'blowing' the box.

So.. does he :
A: Go to the local Merc Dealership (either Rivervale or Greenoaks- I forget which - in Reading)
B: Go to the original dealership in Cornwall who pulled the plug
C: Go to his local Merc 'specialist'
D: Go back to Austria where he bought the car
E: ?????

Here's hoping for a speedy reply!

Many thanks