A letter of complaint

First, you say that all teachers are native speakers. But no, most of the teachers are Vietnamese. Second, the advertisement says that each classroom has just over 20 students, in fact there are more than 30 students in a class. Neither books nor cassettes are free and they are very expensive. Worst of all, the classroom has no air conditioning, and only a few fans. In the end, the class started very late but ended very soon.