Can a car-rental company take money out of my account without authorization?

I'm SO ticked off right now....I feel like I could turn into Incredible Hulk and like, break a brick with my bare hands. Ok anyway, We got a free car rental from Enterprise while our car was in the shop. (Someone rear-ended me when I was driving my bfs car) So when we went to get the rental car, they told us we wouldn't have any fees except for a $25 security deposit that would be refunded when we brought the car back. During the 3rd day we had the car, we get a phone call saying that we owe them $40 for rental insurance. So I gave my boyfriend my debit card and said he could use it for the fee. The next day after we gave the car back, my boyfriend calls Enterprise asking when he will get his refund. The guy tells him that he's not getting a refund because they took it and put it toward the rental insurance and that we also owe them another $14. (When we were told rental insurance was $10 a day). My boyfriend said he would personally come in and pay it because he had some questions