[Saunders]

Mercedes say in the online instructions, that it can take several months as an OTA update, which is why I have always downloaded it manually; it only takes a few minutes.

They don't use peer-to-peer for their OTA updates, so there is potentially huge overheads on their servers in sending data to all MB cars on the road. I'm guessing this is why the map updates can take so long and why they don't even attempt to push out their non-essential cosmetic updates, which are probably large files because of the graphical content.

 

[Saunders]

Yes, you need to remove older map versions from the drive before downloading the new version.
I also received the email shorty after download. I suspect that any activity on your account, including downloading maps - generates the email.

 

[Saunders]

I would use a pen drive that has nothing else on it. I've never had one fail using that method, and I've probably done five or six since I've had the car.

 

[Saunders]

It's a map update. So I'd guess it's roads and suchlike

 

[Saunders]

I believe that on occasion it can get into a bit of a mucking fuddle with this, the download has started so the car thinks it has it but it hasn't been installed so you can't see it. But perhaps someone else could confirm if this is true or just a figment of my imagination

Spot on; I've had this happened to me. In fact, the Me app randomly shows different versions of the versions installed, it must refresh each time the app is opened. The reliable information of version is the one that shows in the car itself. Ignore any of the fake news that the app tries to fob you off with and once you have installed a new version, stop the count (as someone else said recently).