Chasing/sending School Kids Home Due To Unpaid Fees

Good day, I have three kids attending to this school in JHB Jeepe's Town. School fees is R13000 per child. Every month they chase/send my kids home saying they owe school fees. Right now I paid R33000 and I have a proof of payment. The director by the name of Mr. Ngwenya did send them home and he told them to tell me that I should pay half of the remaining balance otherwise they should not come back. And he actually even promised to remove them from that school. Management at this school is bad/terrible. When I ask why do they send my kids home and admin lady told me that it is a private school. This kids are in grade 11 going to grade 12 next year. I honestly regret the day I decided to enroll them in to that school. I will never suggest anyone to take their kids to this school. I wish and hope someone from the department of education can read this and do something about this.