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Marquis790
The rep is incorrect. NZ flies to the islands year round on own metal. Perhaps the rep was confused about timetable. As with most (all?) airlines there are 2 major annual timetables northern summer and northern winter.
UA doesnt fly between LAX and PPT, that is a codeshare on NZ. Travelling between the islands wont always need to backtrack to AKL. There are flights between eg NAN and RAR, RAR and PPT, APW and TBU. For more info see
NZ route map. Note a lot of these flights are only a few days a week, so here is link to
NZ schedule