Economy Rent a Car

I, Eugene R. Shelton made reservations for pick-up on Friday June 16, 2017. Upon at Richmond Int. airport I proceeded to the Dollar rental car counter. After presenting confirmation number, we presented a debit card. The counter person informed us that without a credit card the transaction could not be completed. They could not except a debit card. On June 19, 2017 account was debited $549.42. Why was this money taken out of my account when we did not use your vehicle? I need the funds credited back into my account.