United Airlines briefly offered thousands of passengers the chance to fly first class from London to Newark for just $75 – or £50 – before cancelling the tickets after realising its mistake.
The airline blamed the website glitch on a 'third party error' and said it would not honour the cut-price cost of the flights.
Thousands of people snapped up the bargain tickets on the United Airlines website, after the blunder was spotted by a travel blog.
It allowed users to book a round-trip flight between London Heathrow and Newark Liberty International airport for 491 Danish kroner ($75) if they changed their host country to Denmark. The flights would usually cost around $6,000 (£4,000).
We will void the bookings for those who purchased tickets as a result of a third-party currency conversion error. http://t.co/KBaXBJCwoQ; United (@united) February 11, 2015
Customers were also able to buy cheap tickets to any US destination from Heathrow, as long as they chose first class or business class.
DansDeals advised people to use a card without a foreign transaction fee – and to not sign into their United account.
But once United Airlines realised what had happened, it released a statement accusing customers of trying to "take advantage of the situation".
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"United is voiding the bookings of several thousand individuals who were attempting to take advantage of an error a third-party software provider made when it applied an incorrect currency exchange rate, despite United having properly filed its fares," the airline said.
"Most of these bookings were for travel originating in the United Kingdom, and the level of bookings made with Danish Kroner as the local currency was significantly higher than normal during the limited period that customers made these bookings."
Many users on Twitter expressed their disappointment at losing out on the too-good-to-be-true offer.
Others seemed to have anticipated the airline realising its mistake.
Noooooooo my implausibly cheap ticketssss pic.twitter.com/0jHzFOfBVa; Alex Hern (@alexhern) February 12, 2015
But some said it would affect their future loyalty to the airline altogether. Alison Keunen, who lives in New York – her husband lives in Manchester – said that she only sees her husband five times a year and had booked a Manchester to Newark flight for $125 after hearing about the glitch.
She said she had been left "incredibly disappointed" that the airline had decided not to honour the cheap ticket deals.
“I won’t be choosing United Airlines in the future,” she said in an e-mail, as reported by Bloomberg. “There are so many other airlines out there, so I think it was a bad move for them to make.”
It's safe to say that I officially dislike United Airlines and vow to never give them a cent of my money. My UK dreams are dead #solame; Jessica Bishop (@savvybride) February 12, 2015