uncommunicated charges and poor customer management

Car ok but I was charged too much: - Quote was R511 -I used the car and I filled up the Tank , they did inspection to confirm everything and they said car is fine and everything is fine but then I was then charged R349.78 reason was car was not full and that was said after 7 days and on top of that they took to long to refund my deposit .such poor customer treatment is not acceptable .