[sobek]

Quote Jurubeba

told her she was wasting not only the opportunity of learning English early, but also her mother's money.

this is a good way and ive tried it before. i made the student aware that he/she was wasting the parents money and that the parent wouldnt be pleased.
if also you could make the parent aware of the problems you are facing during your class.

However, those ideas are "destructive" and may not help to motivate the student and may even reverse his/her motivation to learn.

Perhaps you could find out what the trouble students interests are and work on that.

You could also try a reward system. Rewards for good behavior and concentration in class could be rewarded with sweets or other small things the students would like.

may i ask what kind of school you work in?