"We wish they'd been straight with us from the start to avoid this nasty shock down the track, when we least needed it," he told Fairfax.
"The public need to be aware of how Air New Zealand behave, and to beware of how easy it is to interpret their wishy-washy communication incorrectly."
Air New Zealand has not yet responded to NZME, but told Fairfax the airline followed its compassionate policy by applying the family's original ticket value towards the new fare.
"In this case the new fares were more expensive than the original fares which had been purchased well in advance, so the family paid some differential between the two. The fare change penalty and service fees were refunded in line with our policy," spokeswoman Brigitte Ransom said.
The difference between the family's original fares and the new fares was large, because they had booked their original tickets well in advance, she said.
"We sympathise with the passenger and his family's circumstances and we are sorry that he doesn't find our compassionate policy to be clear."