I've had this waived before when explaining I could not book via the website, but you must request it. Usually I call the website support number 0800 352 266 not the main contact number.

Did the agent on the phone ever mention this service fee, or what the total amount you would be charged be including fees? If they did, then you might be out of luck. If they didn't, then they'd be in breach of the fair trading act.

In that case I'd call back and calmly explain the situation to them.

I find that most of the times the airline bets that a customer will swallow fees instead of investigating and pursuing their consumer rights. I've had long conversations about fees with agents that contradict the airline's own T&Cs. Resolution usually happens after I mention writing a letter to them and the Commerce Commission.

I understand how frustrating these fees can be, but always remember it goes a long way to speak calmly and politely to agents. The person on the other side of the phone is at a job taking a LOT of phone calls a day. Help them help you.

Good luck!