As above, I do the installs in your area for http://www.ultimatebroadband.co.nz/rbi-wireless.html
There are a few patches of 4G covering some of your area, and much more to come. I recently did an install up Hanham road and customer gets speeds of 40Mbps+.
On our enhanced 3G plan, we can offer a lot more data than on 4G plans. Speed would depend on where you are and signal strength etc. I have another happy customer in the area who typically gets 15-20Mbps on their 3G plan. These speeds are not guaranteed of course, as RBI is a regulated 5Mbps+ service, and there are some 3G sites around that are quite busy too.
Feel free to flick me an address via PM or email if you are interested.