Europcar is refusing to reimburse me my money

I booked a car, on 26/11, with an unlimited mileage offer via rental cars.com. I paid upfront for the car rental and the deposit when I picked the car. I returned the car to Kruger Mpumalanga Airport on 30/11. Europcar debited from the deposited amount , he day after I returned the rented car, charging me per kilometre,. I have proven to Europcar that I booked the car unlimited mileage. They are refusing to reimburse me my money, instead sending me from pillar to post. It is non of my business what their issues are with their agency, rentalcars.com. The contract and invoice I have is from Europcar, not the agency.