Welcome to the Community @Ernie, I have moved your post to an existing topic about built-in GPS systems and their costs and problems.
Is this a new vehicle or an older 2nd hand car?
If new, then if they, Mercedes, as part of the purchase gave you a contract that gave certain benefits regarding map updates or it had advertising that said they would provide X number of updates for some period of time eg 5 years and on the 2nd service (I am assuming it is the log book service) they couldn’t provide that update as they have ceased their arrangement with Garmin you may have a case to seek compensation under ACL as the car, it’s built in accessories, and stated benefits are not as described.
If an older vehicle then this may be a more difficult case to get any redress. There have been a number of posts on this site regarding built in GPS units on vehicles that mention lack of updates, the cost of the updates, and that updates can be very old compared to non built in GPS units. This current topic has many of those posts but so does the link below.
