Head to Reports then ACC Appointments Not Paid.
The Appointments Not Paid will show a list of ACC appointments for the selected date range that have been invoiced and not yet paid.
Edit Invoice Number: if the appointment has the wrong invoice number, you can add the correct invoice number. When adding the new invoice number you have the choice of changing the invoice number for that particular appointment, or changing all instances of the old invoice number to the new invoice number.
If you wish to remove an appointment from the unpaid list, click on the Ignore button.
You can re-check if a particular invoice on an appointment has been updated to paid by clicking Check for Payments button on the appointment line.
Clicking Check Payments button in the right side bar will check all invoiced appointments in the selected date range.