Bad customer service

I hired a car with Thrifty in PE. The staff was helpful during the booking stage. When I arrived in PE the deposit was held on my credit card. I returned the car on the agreed time. 2 weeks later my deposit was released and it was about R1300 lesser. I called Thrifty and the lady I spoke with mentioned that they took petrol and km amount. I told her that the car fuel was added full and that was even confirmed by the lady who received the car. She promised to send me the invoice so that I can see what was deducted and she never did. A day later I sent an email to customer care and no one responded to my email. I am still waiting for someone from Thrifty to explain the deductions. I feel ****** and I am not sure if this is what the company does just rob people on their deposit by deducting fuel and kms that were not used.