Karen McDonald recently discovered what it costs when you show up at the airport with luggage you hadn't booked to take. But she also learned there's a much cheaper way to get around the problem.

We turned up at the airport last Friday morning all set for a long weekend in Auckland.

I booked our tickets nice and early to secure a good price - just a seat. We’re only away for the weekend, I thought - a carry-on bag each will be fine!

But that was six weeks ago.

On Friday, we turned up at the airport having completely forgotten I’d just bought seats.

Two bags had to be checked in. That will be an extra $120, the machine says.

After my initial thoughts of “that can’t be right”, my frugal carry-on decision comes flooding back. And now I get to pay for it - at the cost of two extra $59 flights.

The irony does not escape me. When explaining my predicament to the Air New Zealand attendant, she suggested I go online and purchase two extra bags for the flight home, for substantially cheaper, as soon as I arrive in Auckland.

And indeed it was - $45 for two bags – more than 60 percent less than what I had to pay at the airport.

I’m not sure how Air New Zealand can justify the difference – but lesson learned!

By Karen McDonald, Consumer NZ's head of marketing and business development.

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