United is pretty clear that the table on their website only applies when the ticket is marketed by NZ, and the ticket is not 016 stock.

This is because to NZ, P is indeed Discount Economy (Economy Saver on NZ) - however when UA issues the ticket on 016 ticket stock, the P fare is a United Business booking class.

Of course this sort of thing is relatively common when cross crediting in this way, the contact centre should be able to fix it up for you relatively easily.