Consumer New Zealand is urging Jetstar to ditch the use of pre-ticked boxes in its online booking.
The consumer group said the airline's pre-selected sections were confusing and could result in people paying for services they did not want.
Chief executive Sue Chetwin said it would take a truly canny consumer to make their way through a Jetstar booking without adding extra charges to the fare.
She said pre-selected services, including travel insurance, seats and baggage, could add $42.95 to the cost of a Wellington to Auckland airfare.
Air New Zealand has removed pre-selected travel insurance after a warning from the Commerce Commission, which is investigating Jetstar's use of ticked boxes.
Jetstar defended the boxes, saying they were legal, clearly displayed and easy to deselect.
Consumer has put a letter on its website asking the company to ditch the ticks; people can download it and send to Jetstar.