Incorrect Fuel Charges

What a disappointment the Bidvest experience was. I filled up the vehicle at OR Tambo airport and returned the car at the same airport, only to be charged for more than a quarter tank of fuel afterwards plus the charge to refuel the car. I only travelled a total of 107km in this car, filled it up and am still charged more than 10 litres of fuel. When I queried the invoice, all that happened was that I was rudely told that bidvest manages over 500 000 vehicles and are the experts but that next time I hire from them, I am welcome to follow the refuelling process. As if I will ever use them again. Shocking and absolutely unacceptable.