The airline is now scrambling to get the affected passengers onto flights before Christmas Day.

Clifton Hill couple Ruth Proctor and Regan Kerekere say the flight change could prevent them from spending Christmas with Mr Kerekere's father, who is unwell. They booked their flights with Jetstar months ago.

But the couple's flight to Auckland was shifted from December 23 to December 28. Jetstar notified them by email on Saturday and said that the change was ''unavoidable''.

''Jetstar is sorry to inform you that since you made your booking, your flight schedule has been changed. We understand it can be frustrating when plans change, and we apologise for any inconvenience caused,'' the email said.

''While we try to avoid any changes to our timetable, in this instance it was unavoidable. The change to the schedule has been made so we can maximise our aircraft utilisation and continue to offer you everyday low fares.''

Ms Proctor said that when she contacted the airline to complain, it proposed putting the pair on a flight on December 18, when they will both still be working.

''It's a month before Christmas, I'm sure they could organise something between now and then, like put us on another flight,'' Ms Proctor said.

''I've explained to them we're going home to visit my partner's father, it's probably the last Christmas we're going to get to spend with him and they've not helped me out at all.''

A Jetstar spokesman said the airline was working to get all the affected passengers onto pre-Christmas flights. ''A small number of Jetstar passengers are being transferred onto alternative Melbourne-to-Auckland services due to schedule changes in December,'' he said.

''All passengers are being contacted by our customer care team via telephone or social media to discuss alternative flight operations… we are focused on doing everything we can to get passengers to where they need to be.''