Poor service in insurance claims

Discovery Insurance is ripping people off on car insurances. My Husband was involved in a car accident. the car was not badly damaged, but they decided to write off my Car since it will cost them more to fix it. I was told the engine is damaged.<br> To my surprise the retail value of the car has depreciated to R53 900 in November 2015 but when check documents on the system, it shows that my retail value is still R54 900,I asked the claims Administrator why it is not updated on the system, she told me it is my responsibility to update the retail value of the car with them every now and then.it means I was gona keep on paying insurance with them only to find out I will not get value of my money.Another thing that am not happy and impressed about is, am not going to get the whole amount ,they deducted R4000 from the Money that am supposed to get . They told me it is for the old damages on the car that the next person who will be buying the car that has been (WRITTEN OFF) to fix it. I don't understand why do i have to pay them to fix the car that they are going to sell on their behalf. they might as well fix the car since I insured with them and give it back to me,