We understand that this could be a bit invasive, however the frequency of the reminder emails is set by the system as follows :
You will receive your invoice by email when it is created by the merchant
As long as the invoice is outstanding you will receive 3 reminders (3 days before the due date, 1 day before the due date and on the due date)
You will receive a payment confirmation when the payment is complete
You will receive a notification when the payment has become overdue
Overdue invoices may still be payable depending on the merchant settings.