My customers are still getting used to the system - as I am - but..

Some users are replying to a previous message to ask a new question. This re-opens the ticket.

The trouble is that I am using time-tracking and at the end of the week I want to produce a timesheet that I then use to bill them. If the user reopens the ticket I'm not sure how I can distinguish which time has been billed and which is new (in the new week).

Can I set tickets so that any reply causes a new ticket to be created if the ticket is closed? How do others handle this?

Simon