I have unlimited data, hotspotting, text and calls on Mightymobile for $20.00 per month (standard cost $40 per month). 

Currently 30% off for Primate users for annual plans. 

Not affiliated, just a happy consumer. 

https://www.mightymobile.co.nz/

Pay monthly plans half price 6 months for new customers

This is a significant improvement and absolutely necessary to remain competitive. 

My entire family have been on 2degrees since day 1, but we've slowly been shifting to Skinny.  We had left one of our lines with 2degrees which is on the $65 plan - we kept it because it's the most cost effective way to have all:

-unlimited calling + texting

-iPad with own SIM x 2

-2 secondary properties with their own modem and SIM cards via the flexible data sharing - this is the drawcard that kept us. 

Having extensive experience on 2degrees, switching to Skinny we had big improvements in signal and internet speeds.  Particularly around Sumner, Christchurch.  Until recently (mid year they upgraded the Sumner tower) 2degrees signal was atrocious, and we were constantly experiencing dropped calls, often only on 3G in central Sumner - whereas Spark has had 5G for a year or two and excellent speeds (up to 500mbps and low ping).

At least now with the 80gb of roll over data, it will keep from ever considering changing this set up as this amount of data and flexible data sharing, well it's a pretty compelling offer.