Schoolfees

I made a mistake as the school finance committee said I've been depositing my sons Schoolfees and not sending the proof of payment to them Milkwood primary school, now they've sent a letter with the child asking me to pay for previous monthly fees August and April, and when they called my husband they said it's July and August we don't know which is which, I went to fnb to ask for Deposit slip reprint and they were only able to help me for August and not 4 the previous ones, now I would appreciate ur help to fix this because the school said I've put a wrong reference on child's deposits slip help me as I won't be able to repay the amount I already paid. I'm in mosselbay western cape, definitely the money is with the School but they don't want to put it under my son's name