We've had a lot of success with osTicket: http://osticket.com/ http://osticket.com/ While it doesn't have markdown or code support natively (that I'm aware of)

We've had a lot of success with osTicket: http://osticket.com/ http://osticket.com/ While it doesn't have markdown or code support natively (that I'm aware of), it's open source so it'd be very easy to implement it yourself.