feedback bbs script

Does anyone know of a script to run, like a bbs, wherein my customers can
put in the bugs they find in their applications, and the followup can be
thus tracked? Something where only that customer can log into his area (and
me, of course), but not into other cusoterms area?

Surely something like this has been put together before, I'm just wondering
if someone knows of a good script for doing this. Thanks, Ike