Guardrisk insurance

I have a MMH top up. I bought a nissan almeira in 2020. In 2023 i was in an accident and the vehicle was written off. My primary insurance paid the market price to the company who did the finance and left me with a short fall. I lodged a claim with the Cmh top up, just to inform me that only R4719. 34 going to be paid to the financial company. According to cmh (traficc) i was under insured. The car was factory fitted with everything, nithing extra was fitted to the vehicle. The vehicle had a factory fitted radio. The professional insurance salesman did not informed me that i have to spesify anything as it was factory fitted and the top up insurance was done the day i received the vehicle from the dealership.