Acer defective laptop refuse refund

I bought an Acer laptop from Game, South Coast mall. It has been sent back for repair twice!!!!!!!!!! First time took 21 days. The day we got it back it had even more issues........ It is under guarantee. The laptop has been in for repair longer than I have had. I can't work due to this. They are refusing to give me a new one. It's obvious this one is defective. I am getting different answers from game and Acer. Game says they still trying to repair and Acer says it's getting a credit assessment. I do not want a lopt that has broken twice in three months. I need a new one. What must I do with a defective laptop.