Poor administration and customer service from Cooper College

My son has left the school last year . We had been paying his fees in advance and provided the school with the required notice when he was leaving. I am still receiving statements from the school for outstanding fees which is incorrect. I have spoken to the admin at the school but nothing has been done to rectify this and I have not received any communication in this regard since my call. I do not get responses to my e-mails to Bronwyn or Jessica in order to have this resolved.