Rented a movie and returned the same day, now I'm ...

Rented a movie and returned the same day, now I'm being charged 30.60 because the machine I retuned it to doesn't show it in the inventory. They don't provide a receipt when returning so have nothing to prove it was returned. I tried filing a complaint but there only comment is that I owe the money and I don't get a refund. If you want to see a movie go to the theater, it's cheaper in the long run than renting a redbox movie! I'll never rent from them again.