I would like to suggest, have a look at Trac's ticket system. osTicket is my system of choice right now for a public ticketing system. But internally I insist on Trac, even when the system is not used for development purposes.

One of the most important reasons is its reporting feature.

Trac does not offer direct email integration and separation between customers and staff, like osTicket does, which is the main reason I prefer osTicket over Trac for public services.