NETASSESS cannot assess at all

I have logged a call with Momentum insure. My son had an accident with his motorcycle. Netassess came out, assessed the motorcycle at a bike shop in PRetoria. First Momentum tell me that Net assess is saying that it is not economical to repair the motorcycle due to the damages that is 75% of retail of the motorcycle. Damages is not 75% of retail and someone clearly need to redo his math calculations. Momentum did telephonically in a few days later confirmed that they realize that the damages is not 75% and actually much lower. Days after struggling I had to hear from Momentum that the actual reason for not wanting to repair the motorcycle is that Netassess said that spares are very scarce. This is absolutely not the truth. The bike shop confirmed that spares are already available. I am wondering can Netassess do their job properly? Do they know how to assess? Or is the problem with someone else. Due to Net assess assessment of the motorcycle, Momentum want to write off a motorcycle that is not even 2 years old. Momentum rely on Net assess to give them the necessary information and in the meanwhile clients are struggling.