Bad Customer Service for Returns

I have purchased a Asus computer for our church and when I arrived home to open up and test I found that it was extremely slow and hangs. I went back to the store and after much struggle they have me a replacement asus machine. The same problem occurred when I used it at church. I went back to the store the next day to return the computer for another one as this brand was clearly a problem. Game Pavilion refused to allow me to purchase another computer even when I was happy to pay the difference for a higher prices computer. They refused the even refund or give me a credit note. I was told that I need to hand in the computer and wait until a technician comes in to look at it. I'm the meantime they have my money and I have no computer