I've been trying to book a partner award on Air New Zealand from Melbourne to Christchurch. United website says there's award availability for the flight I want, but when I try to grab it, the transaction errors out. (Weirdly, the flight comes and goes: it appeared on Sunday, then disappeared yesterday, and is showing again today). At this point, I'm assuming this is a phantom award.

Multiple calls to web support haven't helped (different incoherent explanations each time, including no NZ inventory). Apart from feeling irritated with the situation and giving up, is there anything I can do?