The $US540 ($670) return ticket from Atlanta to Auckland seemed too good to be true.
When American Jennifer Lutz booked the fare through the Student Universe travel website, she quickly received confirmation from Air New Zealand of the cheap trip from Atlanta, to Auckland, then on to Sydney and return.
Then Student Universe called her on Friday to say the flights were cancelled. So Ms Lutz called Air New Zealand and was told the airline would not honour the purchase because the fare paid - about a quarter of what she would normally pay - were mistakenly advertised at very low prices.
An Air New Zealand spokeswoman confirmed that on Tuesday (US time), flights from some American cities to New Zealand were accidentally advertised on third-party websites at roughly 10 per cent of their intended value.
This meant some one-way fares were advertised for about $US100. All customers who bought the "mistake fares" will be refunded.
Ms Lutz, who was set to join her partner in Sydney while she does a medical rotation, said she was disappointed Air New Zealand were not honouring the confirmed tickets.
"I had already begun booking hotels and other travel based on those travel dates. As far as business practices go, it is certainly dishonourable. I will not be rebooking with Air New Zealand if I can help it.
"I know many others were impacted as well and have already set their hotel and vacation plans. What a mess."
The Air New Zealand spokeswoman said: "These fares were available at that price as a result of a genuine human error in the data entry process. They have been cancelled and customers will receive a full refund from their travel agent.
"The US Department of Transport regulates flights to and from the United States, and we are following their guidance on mistake fares [the loading of 'mistake fares' is an occasional issue for all carriers given the manual processes involved].
"In addition to full refunds, any legitimate out-of-pocket expenses that the customers may have incurred will also be reimbursed.
"We apologise to customers for any disappointment as a result of this error."
People who bought the mistake fares expressed their disappointment.
What kind of incompetent company is Air New Zealand that cancelled my tickets after 24 hours of being bought.If I made a change to my tickets after 24 hours they would have charge me but @FlyAirNZ can do that after 24 hours? @RenesPointspic.twitter.com/bOqQjkAkSI??? Susan Ramirez (@Susan45143110) January 25, 2018
Others said Air New Zealand had offered genuinely cheap flights in previous years, so customers could have easily believed the "mistake fares" were legitimate.
A 1975 High Court case ruled that issuing a ticket does not amount to an agreement to carry a passenger, in part due to the number of things that can affect the reliability of air travel, and it is merely a receipt of payment.
The agreement is only reached when the flight goes ahead, the court found.
The story 'What a mess': Airline accidentally offers overseas fares at 90% off first appeared on The Sydney Morning Herald.