I rented from Dollar about a year ago--my only complaint was that returning the car at about 7:00am on Sunday morning, there was noone with a scanner to check you in. You had to go into the office and wait in line. There was one could trying to rent a car with some sort of difficulty--either no credit card or DL issues,not sure, and two guys trying to return a car and pay cash--but they had damaged it.
Anyhow after waiting in line that didn't budge for almost half an hour, I dropped the form and keys in the box and walked away without the receipt--figured I'd rather argue it out with them later than miss my flight.
Anne