A New Plymouth man who has been saving his air points for 16 years was horrified when he discovered all 400,000 of them had expired.

James Wallace, 39, had been saving his Qantas Frequent Flyer air points since he went on his OE in 2003 and had been basing his financial decisions and purchasing habits around where he can earn the most points.

In December, Wallace checked an email account he had not used in a while and was shocked to learn that his impressive accumulation of frequent flyer points had expired - despite being advised on multiple occasions that they would not.

The air points, according to Qantas' website, were enough to buy about nine one-way tickets between Melbourne and Los Angeles (excluding taxes).

Wallace says he got in touch with Qantas who gave him the option to take part in a buyback scheme in order to be able to redeem his points.

The first proposal was that he would need to accumulate 2000 points in a period of six months to have his 400,000 points reinstated.

He told a customer representative he was not in a position to spend that amount of money to redeem the equivalent in points and the threshold was then reduced to 800 points but Wallace says he responded saying he was not in the financial position to do so.

He has not heard from the airline since.

"I entered an agreement for Frequent Flyer knowing that the points wouldn't expire and now they turn around and say they want me to spend more money to get them reinstated," says Wallace.

"With a young family and one income the last thing I'm going to be doing is spending money on anything more than I actually need."

Wallace first got the ANZ Qantas Frequent Flyer credit card when he was 23 before he headed off on his OE as buying the flights on the card enabled him to receive travel insurance.

"When I came back from the trip and had air points on there I just always kept using the credit card for everything and at the end of the month I would pay it off."

He even purchased a family car for $15,000 on the credit card, despite having the money to buy it outright, so he could get the points.

About two years ago he changed from the Qantas Frequent Flyer card to an ANZ Cashback credit card as he says it made better financial sense.

Wallace says he and his wife had been saving the air points to cover the air fares to the UK for their young family of five to visit friends.

The couple made the plan a few years earlier, working out that the points would cover almost the entire price of air fares for the family, but put the plan on hold when they found out they were having twins.

They were hoping to revisit the idea again this year, Wallace says.

"We wouldn't go unless we've got the points. There's not a lot of chance of us being able to afford that [otherwise]," he says.

"If I knew they were going to expire then I probably would have just gone and used them on 10 iPads or whatever you can get online for them."

Wallace says every dollar spent on the card equated to one Frequent Flyer point which meant he had spent more than $400,000 in credit in the past 16 or so years.

In a statement, a Qantas spokeswoman said when customers sign up to Frequent Flyer they agree to terms and conditions such as that air points do not expire as long as members use or earn at least once point within an 18 month period.

The spokeswoman said the airline gave customers a 60-day warning before expiry.

"New Zealand members receive notice of points expiry via an email and, for the full 60 day period prior to expiry, a warning notice is posted at the top of their online account page and in the Qantas App," the spokeswoman said.

"In some cases, Qantas gives customers the opportunity to have their expired points reinstated through an Active Points Program challenge, where members are set a small points goal to help them remain active in the program."

Qantas is standing by its offer for the man to buy back his air points through accumulating 800 air points in the next six months.

Buying a return air fare from Auckland to Queenstown works out to be the equivalent of 800 air points, according to Qantas' points calculator.