Agnew Mercedes Benz - Woeful.
I've been restoring my Mercedes C200 coupe for several months, and it's nearly finished - I brought it to the dealers for very specific repairs, only to be told that the mechanic was 'afraid' to diagnose the stuck sun-roof, in case he broke it. I was then charged for 2 hours labour to change door seals that should have required at most 15 minutes each. I was also charged for repairing a design flaw that causes motor oil to wick through the engine wiring loom. I had agreed to £1800 pounds in repairs - which they couldn't do because 'autoglass' wasn't available to remove the glass from the hatch - for several days, because they can't do that at the dealer.
Basically they made it ultra clear that they could only work on my car under the following conditions: 1. I had to leave it with them for an indefinite period of time. 2. I had to agree to pay over £3000 for an entirely new sunroof (and all mechanics) before they would try to fix mine at all (which is merely stuck on the left side). 3. They will not do 'complete' repairs if electronics attached to glass is involved, relying on third parties to accomplish anything related to glass - and they have no priority for this work with their providers.
Ultimately, the worst part is that they put an uninformed agent in-between you and the mechanic - so the mechanic can say whatever they want to the agent or the back office, the agent then just tells you that they don't understand everything because they are not mechanics. When I did speak to the mechanic, I was assured that all would be done, but the agent failed to coordinate the glass work in time, so nothing happened at all. - But I still got charged over £500 for what should have cost about £100. I will never buy another Mercedes - just because of this and I'll never recommend anyone else do so either.