You can park for up to two weeks in the Fourth-William parking structure for $2. Not $2 a day, but $2. That’s the sweet deal if you take the AirRide bus to Metro airport ($11 one way). The AirRide–a contracted Michigan Flyer bus–is a breeze, even offering free bottles of cold water in an ice-filled compartment to sip during the quick run to Metro. But there are still a few glitches to work out. Recently a departing AirRide passenger asked the bus driver to stamp his parking ticket, but was told instead to fill out a form. Ten days later, when the passenger returned, that driver, too, couldn’t be bothered to stamp his ticket.

Exiting the parking structure, the traveler explained he’d been on an AirRide trip. The Republic Parking employee charged him $2. But no sooner had the traveler pulled away than the attendant, realizing the ticket hadn’t been stamped, yelled at him to come back–and to pay $253. When the driver refused, the attendant threatened to call the cops, and took down his license plate number.

TheRide’s Al Thomas says that of the 20,000 people who’ve taken the AirRide since it began in April, he knows of only three other incidents where drivers were overcharged because their parking tickets weren’t validated. Thomas says that in every case, the transit authority reimbursed the excessive fees–and that he’ll “reinforce” the message that Michigan Flyer drivers need to stamp those tickets.