We can create a Journal Entry to write off the R6.80 on the invoice, lizelle-cjctax-c.

Let me guide you how:

1. Click the + New button and then select Journal entry.
2. Select Accounts Receivable in the ACCOUNT column.
3. Enter the R6.80 amount on the CREDITS field.
4. Select the customer's name.
5. In the next line, select the offset account and enter the amount under the Debit column.
6. Click Save and close.

Afterward, we'll have to apply the JE to the existing credit. Here's how:

1. From the + New button, select Receive payment.
2. Enter the name of the customer in the Received From field.
3. Select the invoice and choose Discounts & Credits.
4. Under the Credits tab, select the available credit and select Done.
5. Select Save & Close.

That should do it! Let me know if there's anything that I can help. Keep safe!