Here is how to use a customer's credit account balance to pay for a purchase.

Step 1: In the search bar, look for the customer and create the invoice that you want to take payment for.

Learn how to bill a student: https://intercom.help/bsport-helpcenter/en/articles/4726929-billing-a-student

Step 2: Click on the invoice in question that you have just created and click on the "Pay via balance" button.

You have just settled the customer's debt with their deposit. You now have access to the invoice in the customer's "Billing" tab.

You can also allow members to use their credit account balance themselves by activating the option in Settings > Billing.