Okay, bad news I'm afraid - GPS/SatNav updates are based on the software installed in the system, which
from what I've read Evesham have now gone bust [
Source 1|
Source 2], and didn't release any map updates for the Nav-Cam 7000.

I've trawled around many different forums which deal with GPS software reviews, hacks and 'modding' GPS devices, but all I can find on the Nav-Cam 7000 are folks looking for updates or saying that they're non-existent.
If you want updated road maps from now on you may want to change the navigation software to something like TomTom or another gps/satnav system. Am sure someone out there has done it before - I've googled a little and there's plenty of folk who've done this. If you're gonna try installing a new system make sure you know how to reverse the procedure and restore your original system though.
Hope that helps

- know it wasn't the answer you were after though...