I purchased a non-refundable ticket from AKL-NAN-HNL for a pretty good price, especially given its Xmas holidays when travelling. I logged in to check J availability on expertflyer and noticed that the flight is no longer direct and goes via APW. The NAN-HNL flight was already arriving at 2am now it's going to be closer to 4am. NZ have dropped their price considerably, so am tempted to just book with them now. Do I have cause for a refund or credit card chargeback for such a change?