SaltyNZ: The 100MB pack is $10. Data packs will now auto-recur; when you use it up, or when it expires, it will be re-purchased immediately provided you have sufficient funds.
Is it possible to opt-out of the auto-recur?
I'm not currently a 2 Degrees customer, but will be shortly. I'm just waiting to use up the last of my Vodafone credit. My wife unwittingly helped out with this on the weekend, but kicking off an update for a bunch of apps on my iPhone. I went out while this update was running. Net result: credit reduced by $20 (only $15.55 to go; Yay!).
So the moral of this story, boys and girls, is this. If you want to switch mobile phone providers, but need to use your remaining credit first, give your iPhone to your wife for a few minutes :-D