Here are three way to refund a payment :
First method
1. Click on the desired appointment
2. Click on Billing
3. Click on the existing payment
4. Click on Refund
5. Click on Save to finish
The mention Refunded will then appear, and the balance of the appointment will no longer be at 0$:
Second method
1. Click on Clients
2. Select the desired customer
3. Click on the Visits and Payments section
4. Click on the two arrows icon to expand the view
5. Go to the right side of the window, in the Transactions section and click on the appointment or class to refund
6. Click on Refund
7. Click on Continue
The wording Refunded will then appear:
Third method
1. Click on the scheduled appointment
2. Click on Invoice
3. Scroll down in the invoice, and click on x Refund
4. Confirm that this is indeed what you want to do
And there you go! 🙂