Thrifty car rental / Sani car rental *****s from customers

Thrifty car rentals has deducted 3 times from my account and saying because its a system error I will only get my refund once the car is returned. I extended the vehicle for 2 days and they have taken money for t days. This agent Demi had no shame. Instead of calling me like I called to in, she sent an email. She advised me on a record line that I will get my refund by 5pm. But instead at 4h32 she sent me an email with **** that I will get a refund when I return the vehicle. In my opinion this is *****ing from a customer. I want my money back - or things can get really ugly when I get the authorities involved.