The worst service ever

I recently joined Bidvest Mccarthy , which offers a home assist service. Part of the service includes things like plumbing and road assist. I called the company on 05 June 2018 to explain that my geyser is leaking. They called a plumber to come who said the element and thermostat is burnt and he installed new ones bought by me. Two days later the water was cold and I called in again. Another plumber came and said the new element was burnt and again they installed an element. A few days later the water was called again. He came and said the temperature was too low and he increased it. Unfortunately the same problem occurred again and this time an electrician cam to assess, and his explanation was that the element was incorrectly fitted, I called Mccarthy to explain and requested that since it is the plumber's fault, either the plumber or the company should buy the element. I also requested that the root cause be investigated to avoid the same problem happening again. I have been going back and forth and all the company does is assess the problem and not fixing anything. Up to today, the problem is still not resolved.