My local MB dealer has been utterly useless, so i'm a bit stuck, and thinking of just ripping out the whole NTG 1 COMAND unit and replacing it. My issue is that i can't get the time and date set correctly. Thinks it's April 2003, and the time is slow by about 5 minutes. Not a major, but it's triggering me hard! There's no date/time option in the instrument cluster, as the instrument cluster clock is getting the time from the COMAND, which is in turn getting the time via GPS. But there's no disc for the GPS, and my local MB dealer has said "Buy a disc! .... from somewhere ..... we don't have them.... so fk off!" - that's pretty much what they said (give to take a word or two

). Buying a disc is prohibitively expensive, especially when i understand that maps are only up to date to 2016. And it sounds like BS to me anyway, as GPS is GPS right, so it should know where i am and set the time accordingly.
So, my question is, if i replace the whole COMAND unit, how does the instrument cluster clock get the correct time? Or does it render it useless? Or is there a specific head unit i need to buy to enable it?
I actually really like the car, had almost two weeks now, but these kinds of little issues are testing my patience - would appreciate some help