Bogus refueling charge by Bidvest Car Hire JNB

On December 2nd 2018 (20:16) I've rented a car (toyota yaris manual) for a day (returned December 3rd 2018, (16:28). I have travelled 76Km. I've topped up the fuel tank about 6 liters of petrol about 3km out of the airport, average consumption is 12.7 km/liter. When returning the car the fuel gauge indicated "FULL" and a little above, just tthe way it was when I collected the car, the company representative looked the car over and did not have anything to say.

When invoice arrived in email, I noticed I've been charged 73.80ZAR for 4.38 liters of fuel and 20ZAR for "refuelling fee". Now, if it is all true then the consumption was about 10 liters for 76km - 7.6 km/liter for a new car (3500km on odometer).

When complaining over the phone, they said they top up every car that is returned so that the next customer will have a full tank, they will check with JNB branch and answer me by email...

I'm waiting...