I've found Spark to be quite reliable, albeit a little more expensive than some other RSP's.

@thisBrian - now you've discovered GZ, I suggest this site can be a good source of advice before making decisions like switching ISPs; there are threads on probably every key ISP - this include Nova's offerings, with the key thread including numerous mentions of their locked-down approach:

https://www.geekzone.co.nz/forums.asp?forumid=49&topicid=245277

I have gas with Nova, and we have regularly been harassed to switch to their internet offering; I may well have been tempted, but had read the thread above so was forewarned.