Here's what 2degrees should do (or Vodafone or Telecom if they are savvy)
The 10-20-30 plan;
That's it, simple, we all know how much stuff costs at all times. Whoever I text it's 10c (whatever network worldwide), whatever number I ring it's 20c (landline, mobile, answer phone), whatever data I use (2degrees or national) it's 30c for 1MB. This combined with auto-topup when below $2.
I know they currently have prepay on 9c/text, 44c/minute, 50c/MB but 9-44-50 hardly rolls off the tongue. In an ideal world NZ prices would be the same as the rest of the world, a 2-4-6 plan would be great but we all appreciate the world doesn't work like that.
I think you might be a little high in those prices. I wouldn't like to be on the receiving end of a bill where a person used a gig of data or spoke to someone for an hour on the phone.
Mind you, having just gone through the experience of adding data to a 2 degrees USB data stick I was surprised to be prompted to edit a * and # code in order to complete the renewal - I am sure that non-IT people would be happy with that experience. I would have expected just to be asked for my phone number in one field and receipt number in another field (or a buy online option) and have the site do the rest.