I was using my iPad with a 2degrees SIM on the introductory 100 MB offer after purchasing a new micro-SIM and noticed that the iPad switched to vodafone. This is in the middle of downtown Dunedin which is encompassed by a 2degrees mobile broadband zone. I manually switched back to using 2degrees as soon as I noticed this. Both vodafone and 2degrees gave four bars of signal on 3G, so I'm not sure why the switch took place. Aren't SIMs locked down to using 2degrees in mobile broadband zones?