Hawaiian Airlines has issued an apology for a glitch that erroneously allowed customers to book travel online without having to redeem miles and overcharged some purchasers for their tickets.

The glitch, which occurred for a few hours on Monday, allowed about 650 HawaiianMiles customers to book travel without having to redeem miles. About 1,300 tickets were issued before Hawaiian Airlines fixed the error and told disappointed purchasers that it would not be honoring the tickets. Hawaiian Airlines said that decision was in keeping with U.S. Department of Transportation guidelines for erroneously priced tickets as well as the carrier’s contract of carriage rules.

In about 82 cases, ticket purchasers went through an even bigger ordeal when the computer read the miles as dollars and billed them anywhere from a low of $17,500 to a high of $674,000 for multiple tickets.

Hawaiian Airlines said it has reversed or refunded all the overcharges and will reimburse purchasers of erroneous tickets for the taxes and fees associated with the ticket.

“We are very sorry and have offered each account holder 10,000 HawaiianMiles to compensate them for their inconvenience and disappointment,” the carrier said.

The carrier also is dealing with issues related to refunds for about 15% of the cases, where purchasers were overcharged in dollars for tickets.

“We became aware of this late on May 21 and began working with our credit card processor to reverse the erroneous charges. We are contacting each of those customers who experienced an overcharge and will, obviously, make them whole and address their specific needs,” the carrier said.