BlakJak:

 

2Degrees can send you what they want for as long as you're their customer.

 

Not at all. They can send service-related notices. Marketing communications are not service-related notices.

They can send something about an upcoming outage on my phone services. They cannot send something about a new service, without an opt-in.

From https://www.dia.govt.nz/Spam-NZ-Spam-Law-for-Businesses: 

The Act provides that the following common messages between organisations and clients/customers are not commercial electronic messages:

    Responses to a request for a quote or estimate
    Messages that facilitate, complete or confirm a commercial transaction that the recipient previously agreed to
    Warranty information, product recalls and safety and security information about goods or services used or purchased by the recipient
    Factual information about a subscription, membership, account, loan or similar ongoing relationship
    Information directly related to employment or a related benefit plan in which the recipient is currently involved
    Delivers goods and services that the recipient is entitled to receive under the terms of a previous transaction.