I think there is a problem here as your phone is from Singapore.
I have some ideas,but that may not answer ur queries completely.
From "locations" u shd download India Maps (its around 200 MB).so use wifi.
For navigation search for some apps in the android market.
Is the voucher from HTC or Tom Tom (maps provider)??
As far as accuracy is concerned, Tom Tom maps are not that accurate when compared with Google maps.
Check out the link below..
HTC Desire HD - Downloading maps or purchasing services
I suggest u to mail/contact htc singapore and explain them this issue, may be they can give you some solution.
Hope u will get a solution to your issue,here on the forums.
Regards,
Kumar.
well, the voucher is from htc and not tom tom.
i did a trial purchase of navigation to test it and downloaded india map.
but i dont like the navigation maps of htc in the locations, its not as good as google maps.
any idea how i can use google maps for navigation even if its paid?