False claim in irregular drivers

After some consultation with a consultant at king price , and mentioning that out of the 3 cars that I have insured, the one car (Kia picanto) would be driven by my son and I , it was mentioned that I would be the regular driver but my son will be also using the car, it was noted and quoted . Unfortunately the car got into an accident and my son who has a license was driving the car and I gave him permission as this was heavily asked for by king price to do so whenever my son used my car. A man named Nomfundo from king price came to our house and mentioned that he is not an investigator he was just there to “tick boxes”. After complying and giving all the necessary information, king price says they will not pay because they claim my son is the regular driver and no proof, evidence or affidavits was given to come to this conclusion, can king price explain how they came to this conclusion because as mentioned the car is used by my son and I ,it is just unfortunate that my son was the one driving when the accident happened. king price decided to use my first call on 3 February when I was just requesting a quote and inquiring about what their policies are and regards to regular drivers , they then used this to avoid paying for the cars damages and have written off a car that can still start, how was this determine if the cars functions are still usable?is this a way of making more money? And frustrate clients ?. they’ve used something that doesn’t make sense to not pay out. King price I would like answers