ORLANDO, Fla. -

Oops!

Southwest Airlines says it has begun filing refunds to customers who were accidentally charged multiple times when a half-price online ticket promotion backfired.

The special sale was timed to celebrate a milestone at the airline. Southwest hit 3 million fans on Facebook, and was supposed to give customer who booked flights on Friday a 50 percent discount on eligible fares.

That offer, of course, set off a burst of ticket sales. Southwest was happy. Customers were happy. Everyone was happy, until hundreds of frustrated consumers started posting stories on social media reporting that their credit and debit cards were repeatedly charged for a single-ticket purchase. Some consumers said they were charged as many as 20 times.

“The overwhelming response from customers who took advantage of our Aug. 3 limited-time offer created website performance issues at various times during the weekend,” the airline stated on its website. “Our employees worked tirelessly to resolve the issue and have confirmed that the duplications are no longer occurring.”

Southwest says it has identified all customers impacted by the problem. The airline has already begun filing refunds to the affected bank accounts and has also agreed to pay customers for any overdraft fees caused by the additional charges.

“Southwest Airlines is committed to providing customers with exceptional service both online and onboard,” the company told consumers. “Our goal was to resolve this issue as quickly as possible to minimize any inconvenience to you.”