Consumer New Zealand has urged Qantas subsidiary Jetstar to improve check-in procedures after a flood of complaints about the airline's service.
A group of rugby fans missed a flight from Auckland to Wellington on Saturday, but Jetstar says the group arrived much too late to board.
However, one of the passengers, Michael Earley, says the group was on time, and a passenger in the queue behind them was allowed to make the flight.
Consumer New Zealand chief executive Sue Chetwin says she has received other similar complaints.
Ms Chetwin says Jetstar may need more staff at check-in counters to ensure passengers are processed in time for flights.
But Jetstar does not believe there are problems with its domestic service, saying it is pleased with its launch into the New Zealand market.
Jetstar spokesperson Simon Westaway says the group of rugby fans who were unable to board arrived 22 minutes before the flight's departure.
The company requires passengers to turn up at least 30 minutes beforehand.
Mr Westaway says staff carry out queue combing and pre-calls before closing off a flight to make sure passengers are on board.
Ms Chetwin says she does not know how Jetstar can claim it has had a good launch in New Zealand in view of the steady stream of disgruntled passengers.
She also finds it hard to believe Jetstar has teething problems, considering the airline is part of Qantas.