Came back after a 24 h trip to collect my car, a CLK cabrio from the airport car park. Driver's window had dropped over 1 cm. I think it was there when I parked in the first place but I was busy and with other people so I must have thought that the window had shut after getting out and closing the door.
On way home I called it at one of the Mercedes London dealerships and, in short, fixed it immediately without charge.
I thought that was decent, even if the cure turned out to be easier than than falling off a log.
(This is the second time this has happened.)
For info, the cure: hit first position of switch to close window and hold for 5 seconds. This reprogrammes the window.
The service adviser had come from BMW only two months before (just to have a change, in case you ask), having also worked at Audi and Aston Martin among others. To him the fault was quite familiar, in fact, also from other makes.
DAS