Review of Inyathi Appliances

i used INYATHI APPLIANCES to replave my Defy thermostat and know on 17/09/2014 , i then noticed that the oven switched off below the heat set , i bought a oven thermometer and tested it and found it switched off about 50 degrees below set heat , i phoned Inyathi and spoke to Marvin who said he would phone me back well he never did , to cut a long story short i have since phoned a few more times and have yet to see a tech come check the thermostat , its been a month now , wasted R820