Frustrating experience with Nedbank Home Owner's Insurance

I recently submitted a claim through my home owner's insurance through Nedbank. The service provider that they secured to assist is absolutely unacceptable in terms of a lack of professionalism and customer service. There was a lot of back and forth to get them to come give the quote, then to come in and get the work done. We have lodged numerous complaints with Nedbank regarding this and they just keep referring us back to their service provider. They removed the frame around one of my plug points and are unable to replace it. They have gone so far as to tell me - the customer - to go find this frame because they cannot. The manager came on the phone and screamed at me, treating me like an idiot and asking me sarcastic questions to make it seem like I was overreacting. The worst part of all of this is that since they have come in to do work in my home, there has been problems with the electricity supply in my flat at the back of the house. We did not have any problems with our flat until they did electrical work in my home. I am too scared to have them come in to assess the problem with the flat because if they caused the issue in the first place I don't want to end up with even bigger problems due to this. This has been the worst experience I have ever had with a service provider and insurance. This claim is dragging out for much longer than it should have and Nedbank will not allow us to cancel our insurance until this claim is finalised. If something as simple as replacing some wiring results in so many problems, I shudder to think what would happen if there was a serious problem in my home that I needed to claim for. I am currently stuck with bigger electrical issues than we had before, an eyesore in my kitchen and the frustration of having to deal with a service provider that is unprofessional and rude. The numbers that they call me from reflect as "House of Beauty" and "Roof Repairs" so I am not even sure if they are qualified electricians. It is clear that this service provider is unable to complete the work. I would therefore like to know if Nedbank is willing to appoint a competent service provider who is able to complete the job and not cause any further problems in my home. A service provider who is professional would also be highly appreciated.