Seems Kogan's 32GB plan new customer offer is back. Or maybe it never disappeared, got this via a Google ad but can't find it otherwise. Expiry date is based on Google ad since there doesn't seem to be one on the page for the deal, only the voucher, but 1 month before the voucher is consistent with what they did in the past anyway.
Before using Kogan, you may want to read the previous discussions e.g. https://www.cheapies.nz/node/21976 and https://www.cheapies.nz/node/21580
The unique Kogan Mobile voucher included as part of this product is non transferrable and cannot be redeemed for cash. Voucher expires at 11:59pm NZST on 30/06/2020. A Kogan Mobile SIM card is automatically included with a purchase of this plan. SIM delivery takes up to 14 working days, after which you can activate your plan. Activation must be made before the voucher expiry date. Voucher does not apply to subsequent recharges. Voucher cannot be used in conjunction with any other vouchers or promotional offers. For information about how to use Kogan Mobile vouchers, click here.
So looks like people will have been using it for nearly a year unless they crack down on people just using a new SIM.
Some new info. Be careful, they have not sent me a sim with this one, even though it is meant to be a part of the package. It took time to even find out that the card hasn't been sent.