R700 to refuel a 38 litre Chevy Spark??????

<p>Avis deemed it perfectly acceptable to charge me some R425.00 to refuel my rental car when I had just refueld it at the petrol station at OR Tambo Airport - not the first time they've done this either!!!!! </p> <p> </p> <p>Brilliant Avis! Brilliant - but do explain how one can get +/- 54 litres of petrol into a 38 litre tan**** I'm sure the car manufacturer would be keen to hear as well </p>