Reservations will not be valid until full payment for the course has been completed. BonaOna reserves the right to refuse admission to students below the minimum required age.

Non-refundable. Except within 15 days of purchase, provided that the camp does not take place within 30 days from the date of purchase. In the case of promotions launched after the purchase, any price difference will not be refunded.

Failure to attend the course will not allow unused days to be accumulated, and no refunds will be issued for individual days.

In the event of cancellation due to medical reasons, date changes may be made or the amount paid may be credited toward other activities offered by the school, upon presentation of a medical certificate.

If you want it more legal/formal or more customer-friendly, I can adapt the tone.