First off, updating NTG2.5 beyond a certain date requires a firmware update (IIRC called 09/29) before updates after a certain date can be installed. Secondly, the last update ever for 2.5 is about 2018-19, no more will be issued. Not sure how to check if you have 09/29 installed, all I do know is that if you try to install the last issued maps update and it's not installed, the DVD will tell you it can't install because of that, it does not try to install, wipe your existing maps then stop!
If you don't have 09/29 installed. comand.co.uk can do it for you (as they did for my SLK, as MB North Wales had omitted to do this for free when servicing the car in its first 5-6 years after they supplied it brand new and serviced it - barstewards who did not reply to my email!! - but it cost. The DVD's I bought "second user" on Ebay or from this forum or t'other side, can't remember. Did the maps update myself and it was easy, just took about 2 hours.
