bad customer service

My little sister joined his driving school on June, and he advised her to pay deposit of 1500 an remainin balance was 1500. R3000 is for 2months. Now she only drove for 4days and Bethuna told her that the truck needed servicing, and that happened for 2weeks. Now all of the sudden his demanding full payment just after his truck came back. And putting all the blame on learners that they broke it..so now question is for drivin only four days is it 1500? If she pays full amount won't he do the same thing?he's very arrogant and rude, he doesn't know how to speak to people at all..