Not from Thailand at the moment, but been there. You don't mention a lot of useful information in your post:
1) What format did you get your map in? DVD, Memory Card, or download? If it was DVD, you could also install it on a computer, and view it in BaseCamp to verify what was there.
2) Are you in Thailand now? If so, the GPSr should show your location on the map, unless you have just gotten off the plane, in which case it may take as much as half an hour to get its bearings.
3) This is primarily a site that deals with US maps. You'll find a more international group here: http://forums.gpsreview.net/viewforum.php?f=2
You should also definitely talk to Garmin if you have a problem with one of their maps.