We own a learning club that offers educational courses on various subjects on semi-annual basis. The contract signed with the student includes the agreed price and payments over the period of the course. The club offers promotional discount to the student who makes payment on time. However, the amount of discount is added to the original price of the course when the student is behind in the payment, as stipulated in the contract. For example, if a course costs (400 JDs), a student is offered a (100 JDs) as a discount provided that he/she pays the whole sum, which is (300 JDs), on time at the end of the course. However, if he/she is behind in payment, then he/she is required by court to pay the (400 JDs). Of course, this is taken care of by the club`s agent or lawyer in charge of the following up and collection, be that via court or bargaining. The agent or lawyer deliver this task in return for taking the amount of the discount offered to the student. What is the ruling of Sharia on this?