Stick with your complaint and push it further up the tree to get a satisfactory reply.
Normally cant fault Air NZ and it does sound initially like a genuine error. Pity about the failure on the return upgrade however
On our one occassion we had an issue with Air NZ, it related to a certain individual at Nelson check-in who couldnt fathom why a couple with baby would take precedence for bassinet seats. It only took one escalation email to get some focus on the issue (and hopefully him demoted for eternity ever after)
Very quickly resolved and they now have a fan for life
