Pathetic work ethic

I ordered and bought a part from spares from Africa in van der Hoff street Pretoria. Their driver delivered the part but I could Immediately see that it was the wrong part. I sent the part back to them. From Saturday until today they haven't been able to find it. I am asking for a a refund but they are refusing. When buying the part no body informed me that they have a no refund policy. The salesman sends me messages from the manager but he isnt man enough to do it himself. I need my money back to get the right part and get my car going. This is my only means of transport and my way of earning a living.