Fridge stops cooling

To cut a long story short, I bought a HISENSE fridge in January last year. In July this year, the fridge stopped cooling but the freezer was perfectly fine. I had called head office and they sent the forms through to fill in and were very efficient. A few days later a guy had come to fix the unit and said they needed to replace the frost sensor. About 2 weeks later the fridge stopped cooling again, I had contacted head office and they said the fridge was repaired so I explained to them what the guy who came to fix the fridge had said and they said they'd look into the matter again. It's October now and whenever we contact head office they say they are looking into the problem. I have to personally call the guy who fixed the fridge every 2 weeks because it stops cooling. There is no response or feedback pertaining to the ordered part, that's if it is ordered. It's a huge inconvenience, not to mention the amount of money I lose on food that goes off. The service is absolutely PATHETIC and I would never buy a Hisense product again.