Nedbank's Service is Highly Concerning

It has taken me three weeks, alot of time and airtime before writing this review, but after having our complaints escalated with no response I don't know who else to turn to. Three weeks ago, our geyser that was replaced by Nedbank's contractors in September 2018 gave in. There were disagreements between their plumbing and electrical contracts with regards to where the fault was. It took us three weeks of calls and begging to have the contractors return to our home today. Within 30 minutes of the electrical contractor being at our home, a part of our property- where I work from- lost all power. We complained to Nedbank but the contractor claims that they did not cause the damage. Three weeks later, I am still without a geyser and now also without a source of income as I am unable to see clients in my office. I have had to open a new claim, despite the fact that everything on that side of the property was functioning untill they started fiddling with the boards causing power failures. Who can I direct this complaint to? A body overseeing financial services?