DALLAS — Southwest Airlines' attempt to thank its Facebook friends with a half-price ticket sale backfired when customers were inadvertently billed multiple times for a single flight — they're not feeling the "luv."

"No, it wasn't a hack, it was just a technology glitch in our system," which caused duplicate bookings and billings to customers' debit and credit cards, Ashley Dillon, a Southwest spokeswoman said Saturday.

The company became aware of the problem around 5 p.m. Friday, she said, when it experienced website slowdowns and saw customers were having to repeatedly refresh pages to take advantage of the airline's one-day "luv2like" promotion.

The special sale designed to celebrate Southwest's reaching the three million mark in Facebook fans was supposed to give customers who booked flights on Friday a 50-percent discount on certain fares.

Instead, hundreds of frustrated would-be fliers wound up posting stories on Facebook about how their credit and debit cards were being repeatedly charged, in some cases 20 or more times for a single flight.

They tweeted and blogged about the related financial hassles, which ranged from drained checking accounts and bounced checks to overdrawn credit limits and canceled bank cards.

Several complained of having to wait hours on the telephone when they called to speak to customer-service representatives Friday and Saturday.

Dillon said Southwest did not yet know how many people were affected and doubted it would release that information when it does get it but emphasized it is working to fix the problem and refund the erroneous charges as soon as possible.

"We are extremely sorry for the inconvenience it's caused the customers," Dillon said. "We realize that people rely on Southwest for great customer service.

"Yesterday a lot of folks didn't see that, so we're working to make it right."