Graduation Refund

The school owes me R3500 for my son's graduation which never happened on the said date so we couldn't attend on another date that was planned due to family commitments. I have been running the whole year and filled in the refund form that was provided by the Institution and even forwarded proof of payment that they requested in order to process the refund. Up until now I am still waiting for them. Please help me get what is rightfully mine. Thanking you in advance