TennisDirector provides for each client, a financial statement that includes all purchases (reservations, memberships, proshop...), payments and account balance.
Cancellations of paid purchases can be refunded into account. Later, when the client purchases another item (reservation, proshop...) the system will highlight that there is a balance that can be used for payment.
Clients may "deposit" payments directly into theis accounts to pay for current or future purchases.
If the client has a credit balance in the account, that credit can be used to pay for any purchases.