One last update:

Went online this morning and all the PE transactions have been reversed, and re-posted at the $130 rate (in all 3 of our accounts).

So it's all fixed, kudos to NZ for doing it so quickly (even though it was the result of a crazy - inconsistent - policy in the first place)!

I have to write to Customer Support regarding a problem on our flight, so will draw their attention to the airpoints policy. One can live in hope that enough complaints may force them to change the policy...