Auto boss auto Maraisburg. Bad service.

I received a very bad service at Maraisburg Boss auto spares. I bought a fuel pump of which I brought the sample to compare the part number and the specs, the guy behind the counter gave me a pump a said its the same. I installed the pump and there was no pressure, you could literally block the petrol with your finger and no pressure at all. I took it back to them and explained that the petrol pump doesn't have pressure, they told me that I cant return an electrical part, I told them that its not the correct specs and they didn't wanted to hear my story. They offered another one which they couldn't confirm the pressure specs and I told them id rather have my money back because they don't know the specs of their products I googled my damaged pump specs and the pressure was confirmed by Google but they didn't know their's. The fact is that they gave me a part that is not working according or that is not a replacement to my one and they refused to refund it. I left the pump and the slip at their counter.