Costa Rica - Dollar Rent a Car

I rented a car in Costa Rica for 11 days from Dec 25, 2007 to Jan 05, 2008. When I returned the car to the San Jose airport location, the Dollar representative coerced me into paying $20 for cleaning of the car (which was only a little dusty), and tried to overcharge me by $200. His behavior was appalling. Since I was so angered by his attempts at cheating me, he ended up overcharging me by only $80, which I have submitted to Dollar for a refund. This is a horrible way to treat Dollar's customers, and leaves a very bad feeling upon leaving Costa Rica after a vacation.