What is the difference between "suspended" and "cancelled"? NZ has either cancelled the specific flight on which you are ticketed or it has not. Also not sure what an "official" notice is. Entirely possible that you will not receive any notice, but will have to look yourself. Then, forget about what you have read and proceed:

1. If the flight has been cancelled, approach NZ for a refund. If there is pushback, just be insistent.
2. If the refund is refused, submit a chargeback to your credit card issuer (bank) and have ready a copy of your e-ticket receipt showing the full routing, the means by which you have confirmed that NZ has cancelled, your demonstration that you requested a refund and NZ's response (or non-response).
3. File a complaint with US DOT. But, remember that DOT does not act for you. It will log the complaint and may take action against NZ. It will also forward your complaint to NZ and require an answer.
4. If your refund arrives after you have initiated a chargeback, simply withdraw the chargeback.

Avoid getting into quasi-legal arguments with front line agents of air carriers.