Milo,
Thanks, I've played with VOIPCheap and still have an NZ account with them - they offer 90 days totally free service after each top of the account, but texts are not guaranteed, sometimes they do, sometimes they don't.
A NZ VOIP service is called 2talk, and that works well, but I had trouble using it when not in NZ, which is why I tried Skype and realised that all wasn't as advertised, maybe it's simple finger trouble on my part, but I haven't solved it yet.