Despite two calls to the airline's support team and three hours of trying, she could not book online.
"I thought, oh well, I'll just do it as I used to do it - ring up and pay over the telephone."
After being stung with the additional fees, the woman complained to Air New Zealand.
"There are still people in the world who are not very computer literate, particularly in the 75-plus group," she said.
"And unless you have family and people that you can get to ... help you, you have to stick to the things you can do, like playing Angry Birds."
The retired teacher and frequent traveller said the fees were out of all proportion.
"I would not have been on the phone more than eight minutes, because I had all the data off the computer - which flights I wanted, the time of the flights.
"I used one credit card to pay for the two of us and I was charged as if two people were booking."
An Air New Zealand spokeswoman said the airline realised not everyone was familiar with booking online.
A free 24-hour phone service was available to guide customers through the process.
Customers who chose to book domestic flights over the phone incurred a $30 fee per person per flight.
The $104 service fee on the woman's receipt was for the service fees without GST for her and her companion's four flights.
"The service fee is a reflection of the personal assistance when booking via the Air New Zealand contact centre or an Air New Zealand holidays store."