standardbank please pay for my car!!

last year on the 8 december i gave my son my car to go drop on his friends in my area, on his way he got into an accident , a drunk driver hit a van and the van tumble into my car, the driver was arrested on the scene as it was his fault, standardbank send accessors and investigators to access my car, which after they wrote of the car and send it to SMD, they came a courtesy car to use for a month, yesterday when i called to enquire on my claim i get feedback that my claim was declined , even thou it was not our fault but the other driver. i want my claim to be looked into by higher authority as i feel this is injustice by one company that i had all my trust in and all my accounts with , i have investments with you guys if this does not get looked into , im taking my business somewhere else, where they honest and treat customers fairly