There is a script used to send expiring alert email and debit supercash from customer account as per the expire date. That script can also be triggered manually from here.

Enter the date and click on run button.

For example if you enter the current date, it will check the records that are expiring today and debits supercash from the respective customer accounts and sends them alert; and also sends alerts to customers whose supercash is going to expire on next X date (X = Send Expiring Reminder day + current date)

If you want to send expiring alert email 4 days before of expire date, you set the field "Send Expiring Reminder Alert before (in days)" as 4. So when you run the script manually from here and you mention for example 15-08-2018, the script will look for records where the expire date equals 15-08-2018 and debits that supercash (unused) from customer account and sends alert to customer that supercash has been debited from the account. Also the script looks for records that are expiring on 19-08-2015 and sends alert to customer that their supercash is about to expire on 19-08-2018 and hence asking them to utilise the supercash before getting expired.