Online car parts

I bought some parts online in February, so every week they are waiting for the supplier. When I asked for a refund, I had to wait 21 days. It's long past 21 days, but still no refund. If I call, they put me straight to an answering machine. I even asked for a credit note to just buy something for my money. No credit note till today. The last 3 days I phoned, and they didn't even answer the phones. The office and cellphone numbers ring, and they don't answer. They are ****mers that ***** people's money.