Car Rental, Insurance, Accidents, Claims

Hi, has anyone rented a car with insurance and had an accident and needed to claim? Was it straight forward, if the car hire people told you you had 1st class insurance and wouldn't have to pay in the event of an accident was this actually the case or did you have to part with more money in the end? If so how much? If they told you a maximum price lets say £10,000 baht, was it just that or was it more? Or when it came down to it was the insurance useless and a complete waste of money? Any experiences greatly received! Am not actually in this position but have recently took a car back, but a verbal exchange after the event leads me to believe the insurance was probably a scam ?