Exorbitant charges for changes and no refund

I needed to change my flight dates back from Cape Town for a meeting. The call centre person incorrectly booked me on the wrong dates. I then had to phone again and change my dates to the correct ones. I was charged double for the initial incorrect change and then the corrected change. When I queried this I was told that they had listened to the voice recording and due to \agent error"I would be refunded R450. That was two months ago. I now send weekly emails to every email address I can get hold of at Saf Air and am just being ignored. Surely I shouldn't have to beg for the refund that they admitted owing me? """