Step 1 : Book the appointment.
Go to the appointment tab -> choose the appointment, the type of session and the time slot you want to register for -> select pay later.
Then click on confirm.
This way you will have booked an appointment without paying any appointment pass. The appointment will appear as unpaid in your history.
Step 2: Regularize the appointment
In order to regularize your session, you must purchase an appointment pass compatible with the session. The amount of credit needed for this session will be automatically debited from the appointment pass you will buy.
Go to pass -> appointment pass -> choose a pass valid for the session
Then validate the basket.
You will then have regularized your session. The right number of credit will be automatically taken from the pass you purchased, and there will no longer be marked "unpaid" next to your session reservation.