Debit for a paid up loan still no refund

I was wrongly debited a loan which i dont owe and which was fully paid by Fnb on the 24th of OCtober , wrote a review ere no one called me only to be called on Saturday after i called to find out what is really going on , the consultant said my money will be sent back to me , up to day still havent received those funds , this not the first time they are doing this last week they did the same thing s it has happened to me twice what must i do to get those funds back , as i really need to use them