Teljoy's Appauling service

I am renting to own a Defy chest freezer from Teljoy I have had this contract for approx. a year. This freezer has broken down three times within a span of six months for the same problem they keep on sending a Technician who supposedly fixes the problem. All I have wanted is for Teljoy to replace my unit with a brand new unit which they are refusing. This puts me out of pocket because I have to throw away thousands of rands worth of groceries each time. Teljoy does not even have the decency to try and make the effort to compensate me. I have spoken to the Customer care and the Technical side and all I get is promises that a manager will phone me back to NO avail.