Filling a car and still billed for petrol.

I hired a vehicle at the Cape Town International airport. On the returned date I refuelled the car just before taking it in. I then got money deducted from my account and called the team. They advised the money deducted was to refuel the car. So i want to ascertain where did the petrol gone to which i filled it up with. They provided a reference number and told me i would be contacted in 48hours. To date its more than 2 weeks and no one made contact with me.