Do they want to pay for it? If you want to call a vendor for support, these are some good options.
Pay-for solutions:
Magic is the best one (in my opinion)
Touchpaper is another option. I don't like the web interface on it, but it's got a lot of options. For instance, a customer can email the system and it will create a problem ticket for them and automatically enter it into the database.
Go to sourceforge.net and do a search. You'll find MANY free ones. You can also google open source help desk and get some hits that way. All a trouble ticket system needs is a bunch of forms and a mySQL, SQL, or Oracle back-end. Queries are made to search the content and user accounts are setup to divide who sees what. It's only complicated because of the number of specific needs each person has.