Search By distance - Zip Code search

Hello Team,
I installed the Search by distance plugin.Its great feature.Its not showing the accurate results for India.most of my listings does not have the zip.I am really not sure how to fix this one and also i found that zip is not showing the accurate location when i tested.
Is there any way we can fix it.By default search by distance map showing different place.

Flynax have very great features..
i have suggestion one suggestion.I am not sure whether it is good one or not but it will be easy maintenance and searching is very easy and neat.Location or address can be make it as fixed so that any configurations does not screw up.

Can we Combine Location on map ,Keyword by distance,Geo Filter plugins,Geo location and come up with the Address always enters will be adjusted on the map while posting the listing (so that users does not do any mistakes) and searching also geo locaiton search (users location) using on google or by search address by combining with distance search by radius?

Regards