Hisense fridge from HomeCorp is poor quality

I bought a Hisense fridge from HomeCorp on 7July during the severe cold. When it got warmer I realised that the fridge temperature is low & doesn't change regardless of setting. Their manual specifically advises to keep the temperature at 4/5 too. I called HomeCorp to exchange the fridge & refused as exchanges are only done on 1st 7days. They promised to send out a Hisense technician to repair it. To date that technician has called me twice & doesn't honour appointments. I want my money back.