I had the same issue with Mercedes Brentford not updating the maps at the A service when my car was 12m old. A query to MBUK about what the policy is on an A service, and MBUK phones back to apologise for the dealer not performing the required service items and I am being compensated for my inconvenience when the car goes back in today.
I suggest any customer who is "unsure" about whether their maps should have been updated makes a call to MBUK with reg number and map version and let them look in to it.
Also, the more MBUK realise the dealers aren't doing the required service items, the better then can quality control, and, also feed back to the design team that the update method is so inconvenient it leads to these issues.