AirAsia X introduced a daily service between Auckland and Kuala Lumpur in March with a brief stopover on the Gold Coast, Australia. It uses an Airbus A330 on the route.
Air fares are at historic lows as airlines pour more capacitiy into New Zealand and are able to offer bargains because fuel prices are relatively low.
At the weekend Flight Centre NZ released record low fares to the British capital - a return from Auckland costs from $1349 per person.
AirAsia X chief executive Benyamin Ismail said the sale fares would go quickly.
AirAsia X will drop the use of pre-selected 'opt-out' services and change how it discloses processing fees when selling airline tickets online after being issued with a formal warning by the Commerce Commission.
The censure was issued over AirAsia X's flights from Auckland to the Gold Coast , when the airline's advertised price for the flights didn't include a pre-selected checked baggage allowance and charged an unavoidable "processing fee."
The airline said today that fares include airport taxes and surcharges but a processing fee is applicable for online bookings made by credit, debit or charge card.
AirAsia X is the long-haul, low-cost affiliate carrier of the AirAsia Group that currently serves 22 destinations across Asia. It operates a core fleet of 31 A330-300s with a seat configuration of 12 premium flatbeds and 365 economy seats.