Bad service

My daughter attends school at Gauteng City College , I accidentally paid the school extra for the year and they refusing to pay me back my money. Why I'm I being denied what is due to me when they return leaners home if they don't pay the fees or are in arrears. They promised to refund me 3 months ago now they telling me it will carry over for next year for what ? Who said i will not pay fees for next year and want my money to carry over for next year, as I'm never in arrears? I'm not pleased on how they operate and my child will definitely not go back to that school next year. I want my money.