Were to get a cheap software or freeware software for my webhosting company?

It has been talked about here a hundred times.

http://www.phpsupportdesk.com/

or www.deskpro.com :)

http://www.deskpro.com/forums
http://www.deskpro.com/features.php

While deskpro isn't cheap, you might want to check out:

RequestTracker
PHPWebSupport
Ticketsmith

.