Chicago Midway International Airport - Economy (Red) Lot

I had about 10 minutes left on my one hour parking. Their was a car in front of me it took 15 minutes for the cashier to check him out. As a result my parking went over (4 minutes) by the time I reached the cashier. She charged me for another hour after calling her Supervisor to explain this situation. This shows no class for the City of Chicago! I intend to file a complaint and request a $4 refund.