Refused to exchange something I bought from them within 7 days 😡

I bought a dishwashing sink from Thompson Sabie, unfortunately I lost the receipt and it was a wrong sink. I went to return it within 7 days and also withdrew my statement so to prove that I bought the sink from them but they told me that they don't sell that sink and refused to refund or give me the correct sink. I'm now stuck with a wrong sink because of their incompetency and worst customer service ever. No more buying from that store