Not to justify the shambles of trying to rebook, but it looks like NZ have put temporary fare ceilings in place until 6 Feb (domestic) and 13 Feb (international), in line with the dates of increased fare flexibility.
A seat only fare for AKL-CHC until 6 Feb is capped out at $188, and AKL-SYD at $415.
Appreciate people that booked ahead may have paid a lot less than this, but there will be some that will be able to take the credit and rebook for the same or less than their original fare without needing to go through the call centre.
I recall that NZ have used fare ceilings in the past (chc earthquakes etc), but often after pressure from public backlash. I can also respect that this in itself isn’t going to be a solution for everyone, but hopefully this saves at least some people the headaches of queuing in the call centre for half a day!