[wolfbln]

"But their telecom infrastructure could be more competitive. It would be nice if there was a third mobile network, so these mobile cos. Had more competitive prices and more consumer friendly attitude."

Well, New Zealand has three networks. Vodafone (with a f, not ph), Spark and 2° (spoken two degrees) and MVNOs like Skinny. That's not bad for competition.

"Second, I can't believe there is no return policy for unopened items. Is it specific to Spark? Is it a general policy in NZ?"

A SIM card or plan is not like any merchandise with warranty and a right to return. Because even a prepaid plan normally involves a kind of contract to define the T&Cs.

All over the world most vendors will stay away from taking back a SIM plan that you have bought in a different store. Even if it looks untouched, there is no obligation to do so. You can do a lot of things with a plan online on your account, without touching the SIM. It's more like a concert ticket, that your ticket agency may take back before the event, but often is not obliged to do so. All you can count on is their courtesy. But you can't expect it between different stores (of the same provider) especially if you want to change a more expensive plan to a less expensive one. I think this is not limited to New Zealand, but general rule.

So let's compare with the US. You can walk in every operator store in NZ and can get a SIM plus 1 GB data for NZ$25-35 (if it's physically available). NZ$30 is around US$20. Which US provider sells me 1GB data for a tablet plus prepaid SIM for US$20? T-Mobile already charges $15 for the SIM alone in their branded stores outside of promotions and AT&T prepaid plans start at US$25. Both operators check IMEI numbers to be sure that I don't activate my "tablet plan" on a different device. If the device is not recognized as one of their featured tablets, I'll be moved to a phone plan with less favourable data rates. This all doesn't sound more competitive to me.