Poor workmanship

Policy number *** On Wednesday 04th December I logged a call about a leak from a drip pipe from the geyser. MandM plumbers who less than a month ago, came to fix the same problem responded. In early November the same plumbers diagnosed overheating as the cause of the dripping. Therefore, they reset it from 70 to 65 degrees to stop irregular dripping.

It seemed okay for some time until last week whereupon, I reported. Shockingly, this time around the diagnosis was different. A valve and a non-return valve were identified as the problem. It is strange that the same company within one month identifies two different problems on the return job. Shouldn't they be held responsible for wrong diagnosis? Now I am asked for R 1260 for parts replacement.

How can I trust them on their poor workmanship?