i think they dont have manners to how to talk with elders so,they behave very rudely with the bus driver.I will tell them "not to converse rudely with any one  even with the bus driver.It doesn;t look good.He is a bus driver it doesn;t mean you should misbehave with him."If they will not listen  to me or again misbehave with bus driver then i will complain to the class teacher.