I tried registering on Mercedes.me and I even went to the nearest Mercedes dealer where he attempted to register me on Mercedes.me but failed. (He said I couldn't use Mercedes.me Connect because my car didn't have telephone services like an onstar button or whatever, and therefore couldn't be registered.)it has to be done by your dealership BUT! they dont know how the only ones who knows how to do it are the UK dealers
basically, the seller has to get into Xentry and get your VVC from your VIN, then he has to register your VVC on Mercedes.me then he has to register your car on Smart Support AND! finally it will appear a phone number in the car, you call to that number and then smart support activate the app.
that there are 3 apps, the 451 (already gone), 453 (up and running but no one has info about it) and EQ only available in Germany.