Of course NZ's position has been reviewed by its "legal team" and that "team" knows full well what it is doing.

First, no refunds for cancelled flights/
Second, refunds for flights to/from the US, but only for US citizens.
Third, some people get the refunds.

Why waste a second on NZ. Make your request, wait 7 days and then on the 8th file a chargeback with your credit card issuer (bank) noting that you were ticketed to or from the US and that US law requires the refund for such tickets. Supply a copy of your e-ticket receipt, the cancellation notice, your refund request, the denial (or a note that no response has been received) and a copy of the Notice and the Warning Letter.

The easier and more self-contained, the better.