"We're getting in touch with everybody and getting them back on that flight, should they want to take it.''
The spokesman refused to say why the original flights had been cancelled: "Just rescheduling that we do from time to time ... That's all we're saying on the matter.''
He said people who could not make the extra flight could ask for a full refund.
Jetstar yesterday vowed it would get everyone home in time for Christmas, but did not reveal how it planned to do that.
No seats were available on the Jetstar website from Melbourne to Auckland on any day between December 18 and 27.
Wellington woman Kara Duxfield was startled by a "casual'' email from Jetstar to say they would change her flight but she would miss Christmas at home.
Ms Duxfield's short holiday in Australia was to finish with a flight home from Melbourne on December 18.
Instead, the airline cancelled the flight and told her the next date they could get her back to New Zealand would be December 28.
"Which is 10 days later [and] after Christmas. I rang them and said it's ridiculous,'' Ms Duxfield said.
Jetstar agreed to put her on a December 17 flight, which fortunately did not interrupt any holiday plans but simply meant her stay in Melbourne was one day shorter.
"I would definitely be much more reluctant [to fly with Jetstar in the future]. Luckily this time it's a casual holiday,'' Ms Duxfield said.
Many Jetstar customers vented their frustrations on Jetstar's Facebook page, prompting others to speak up and say they had the same problem.