This is the worst car rental company I have ever me across!

I rented a car from this car rental company on the 23rd of December 2020, having made a reservation on the 22nd. On the day I made the reservation telephonically I received and email confirming the reservation which stipulated that the rental price includes vehicle insurance amongst other things. The vehicle was involved in an accident being driven by the additional driver I had added to drive the vehicle. Then in January without any communication from the company they deducted from my credit card an amount of R10752.50 which upon enquiry they sent me an invoice for damages. I further enquired why I was paying for damages on a Vehicle that was insured and I was told it’s excess. I am not happy with this information as excess and damages are two difficult things they have now written me another email that they want more money an amount of additional R4277.00. First what informed their first deduction from my credit card if they didn’t know the actual amount and also why would I pay for damages on an insured vehicle? This is the worst service I have ever gotten from a rental company having rented vehicles for the past five years.