The ability to set custom reminders for invoices, same way as Freshbooks does it. Currently I am limited to the defaults timeframes for sending reminders but when a client is late I want to follow a different sequence eg Late Reminder, Warning, Service Suspension. All at different days after the previous email. https://support.freshbooks.com/hc/en-us/articles/227559727-What-Are-Payment-Reminders-and-Late-Fees-