Maybe, this is a norm in every driving school. It does not occur only in Al Khebra but in other school also. Instructor's salary is very small so they resort to take money from students as extra income.

Filing a complain in the management is the right way if the student is not there anymore. Otherwise it will jeopardize their schooling, such as delayed recommendation for driving test, failed Driving test, and worst of it is failure to get a Driving License.
So, to avoid these inconveniences, the student will "just go with the flow".