Airport officials say some problems involved scanners not properly reading toll tags, leading to overcharges when wrong times for entry or exit are recorded.
The airport says all overcharges will be reimbursed within 10 business days.
"We are very apologetic for the whole thing," airport spokesman David Magana said Thursday. As many as 300 to 400 drivers have called the airport daily to complain about billing errors.
Beginning Sept. 4, an upgraded payment system automatically registered vehicles driving in and out of the airport complex. Drivers can process their own transactions with a North Texas Toll Authority TollTag or a credit card as they exit.
Some drivers complained about being charged for parking times after they had already left the airport.
Dallas resident Bill Woster received a $108 airport parking bill on his TollTag account after spending about 10 minutes at the airport to drop off a friend.
"I was shocked," Woster said.
Officials believe he'd briefly been at the airport a week earlier and the new system failed to read his TollTag when he exited, so when he returned days later, the system calculated the charge as if he never left.
"How many people didn't look at their toll charges every time," Woster said.
Airport officials are also going through records to catch any billing mistakes.
"We're a customer-service business," Magana said. "You shouldn't treat your customers that way, and we certainly never meant to treat them that way. It's a mistake and we're fixing it."
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