I have an upcoming trip SFO-AKL-SYD-SFO in mid November booked on Air New Zealand with the return SYD-SFO on NZ9870 which is actually UA870.

I am a CO Plat but have no status on UA. I entered my UA MP # and can view the itinerary on United.com. I would like to buy a one-time E+ upgrade but United.com gives me the error message "No travel options available at this time, please check back later."

When I called and spoke to a reservations agent they told me that Travel Options are not available with codeshare flights.

Has anyone found a way to buy an E+ upgrade on a UA operated NZ flight?

If I purchase annual E+ access, will UA let me sit in E+ on this codeshare flight?

I'd appreciate any advice you might have. Thanks!