I made a car rental reservation through cartrawler.com (dtag thrifty usa) for May 23rd 2012. Reservation # MX270665730. I cancelled on April 20, 2012 and was told when I cancelled that a 33 dollar cancellation fee would be charged. The reservation was 50 dollars, I think this is abusive.
Did you cancel more than 7 days after you made the reservation? If so, then that is in accordance to their stated cancellation policy. Hard to call it a ripoff in that case.