Defy chest freezer faulty

Bought a freezer online in June. Delivered from Makro Crown Mines and since receiving it had endless issues. Doesn't freeze and stay frozen. Lost several hundreds rands of food already because it defrosts and spoils food. I logged an enquiry with Makro in June. They logged a call with Defy and technician came and checked and said wire was not connected. A week later, it gave same issues. Contacted Makro again as Defy says I need to go to the service provider. Makro logger another call with technician who came out and changed the thermostat. 2 weeks later the freezer has defrosted once again. Called Defy who again said I need to go to Makro. Call Makro call centre. Told the agent that I want a refund or an exchange as something is clearly wrong with the product. I held on the line for about 20 minutes whilst shr went to speak to her supervisor. I had to disconnect after that time as I had a meeting. I log a query online with the details online to find out Makro has logged another call with Defy!!! I have sent them countless emails telling them I don't want Defy coming out again as there is clearly an issue with the freezer. I want a refund or exchange. No reply and have been emailing asking for updates but nothing. I'm at my wits end with this and the lack of feedback from Makro! Please help!!!