GPO Ripoff

I had read both positive and negative reviews and decided to give them the benefit of the doubt. I now regret that. I had placed an order for the spare part and paid R2500 on 17 April. I did not hear back from them. I emailed, whatsapped and phoned. When I eventually got hold of Erika, I was told she would get hold of the courier. That problem lasted for a week. Eventually on 16 May, almost a month later I was told that they did not have the part and would refund me. I sent the banking details that day and I am still waiting. My calls were then avoided. I was informed that I would have to get hold of Kobus Herbst. Well I am still trying, while they sit with money. What recourse is there?