Good morning I have a problem and i would like to be assisted on this matter

Good morning I have a problem and i would like to be assisted on this matter. I accidentally paid my nephew's UNISA fees with an extra R500 on February. So my nephew contacted the school and he was requested to email proof and some documents of the account holder. He has done that and so do i. Every email they keep asking for the same documents. Now it's June and i have not received my refund of R500.