Need a web developer who know about coding for my ticket website

My joomla site has an ticket event system where customer can book/buy e-ticket, the event system is call event nova the problem I'm facing is when someone go to buy a ticket they get to the registration part and the system will genarate their ticket like they have paid for it but what we need to happen is they register then when they have paid for the ticket the system will email the ticket at that time not before .