When you make a mistake on an account as it relates to payment, here's what happens:
The mistake is recorded in the Transaction History, which both you and the Customer can see (if by chance they are signed in to their account and are looking)
The mistake can easily be fixed by you, after which the mistake will either be deleted or corrected by an additional transaction such as a credit
The Scenario
Let's say you accidentally charged someone for tuition ($150) twice. One charge happened automatically on the 25th of the month by Enrollsy's auto-billing system, and the other charge happened a few days prior because you forgot about auto-billing and manually added tuition.
Then Auto-Pay ran on the first of the next month and collected a total of $300 from the customer. You notice this before the customer says anything and you panic.
The Solution
Don't fret. This is an easy fix. Follow these steps:
Open Enrollsy and search for the Customer in the top search bar
Scroll down to their Transaction History and click the three dots beside the Customer's payment
Go to the Invoice the payment is on (if applicable). If the payment is not attached to an Invoice, there should be an option to Refund (it's NOT the same day; if it is the same day, you can VOID the payment).
Click "Refund" to issue a partial refund of $150
NOTE: Make sure you add a Credit of $150 on the Refund step to balance out the account.
When you're done, the balance should be $0.00 (assuming they had a $0.00 balance to start with).
Conclusion
The Transaction History that is kept for each account is a credit and debit history. Charges result in debits to the account (meaning they owe you money). Payments result in credits to the account (meaning they paid you money).
When a mistake is made in someone's financial account, the important thing to remember is that depending on what the mistake was, you may need to fix both the credit and debit sides of the transaction.