Refuel an already refueled vehicle.

I rented a vehicle vw vivo from Bidvest car rental and to my dismay i discovered like eveybody else what a ***** car rental they are. When i returned the vehicle i filled the vehicle with fuel. They subsequently charged me a refuelling fee and fuel service fee claiming they refueled 11.35 litres of fuel. It is highly impossible to use 11.35 litres of fuel for a distance from Shell, Gateway to King Shaka International Airport. (Dist 13.9km) . Initially they tried to charge me for damaged rim on the vehicle ( which i didnt do) and decided to ***** me in for a lousy R280.20 for fuel. People do not hire from them they are desperate and *******s.