Overcharge on petrol

I picked up the vehicle at lanseria Airport at 8.am on the 25th May and Straight away drove in economy mode for the 6 Hours I had the vehicle, I coasted down the hills in neutral and never went over 80KMH at any stage.<br> I used the Ford fuel NEDC L/kM combined cycle average 5l/100KM and was very disturbed to see that 12.33 litres petrol was replaced into vehicle, which means I should have driven approx 246 Km's. I actual fact I drove 97 KM!!!<br> This is not the first time I have experienced this, and have had to expose this sort of abuse or going on at either the depot or branch.<br> I am not at all happy and am shall not be using AVIS in future.