Appointments+ confirmation emails not (re)sending.

My client wants to have a required payment at the time of booking an appointment and have all appointments need confirmation by her.
At the moment, if the send email on confirmation option is checked, the system is sending the confirmation email immediately (before the appointment is confirmed). If this is unchecked and in the appointment details you check the (re)send confirmation email, no email gets sent.
What do I need to do, to have the system require payment, but wait to send the confirmation email until my client actually confirms the appointment? Thanks.