i booked my SL in for a map update at cost of £100 at Mercedes Stourbridge dealership, I just checked and it says map version 2017/2018 I’m not sure this is the latest ?
If they insist that they installed the latest version, just give them the MB part number from my previous post.
BTW, I imagine that v19.0 might be out soon.... the new versions are usually released less that a year apart (v17.0 was released in June 2018, v18.0 in November 2018).