Last August, I joined One NZ on the "Get $300 Credit with Unlimited Fibre Max Plan on a 12 Month Contract ($105/Month + $14.95 Modem Fee or BYO) @ One NZ" offer. The move was quite seamless from contact to One NZ.
Since its been >1 year, was thinking of moving elsewhere and whatsapp chat drops this:
"About the 30-day notice: if you’re transferring your broadband to a new provider, the notice period starts once your new service is active. "
Its like legally saying you can move to any provider, any date in October and we will keep charging you for one more month from there on.
How do you circumvent this??

That makes no sense at all, dispute that.