When Marion Sessions went online to book return flights for herself and her husband to Faro, she probably thought she'd be able to bag a bargain.
Finding a deal for £164.07 on the eDreams website, she was hovering over the 'Click to buy' button - and then noticed the small matter of the price. She was about to be charged £23,659,382,125.95.
Posting a screengrab of the 'deal' on Facebook, the Derbyshire resident joked about the rather expensive flights.
"Don't think our current account would have run to it this month," she said, as reported on the Sky News website.
Ms Sessions has written a blog about her experience, which she claims left her 'shaken'.
"What would have happened if I had [purchased the flights]?" she wrote. "Neither of us has £23.7 billion to spare. What would have happened to my credit rating?"
She tried to call up eDreams, but found the office was closed. However, she did receive an email a few hours later, saying: 'Don’t miss out on your dream flight deal to Faro!'
eDreams has yet to contact Sky News or Ms Sessions with an explanation.