looseleaf: Be aware you get two year warranty if you buy from authorised distributors (JB, Telecom).

There are some unpleasant stories about trying to get any warranty support at all from parallel importers.

 
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Although mobilestation in my experience was good when a mobile I bought from them died. Fast response to emails, kept me relatively updated, and got the phone back within the stated timeframe.

My experience with Sony NZ warranty has also been good, easy to call them 0800, they sent me prepaid courier box, live updates etc.

The other difference is 2yrs warranty through official suppliers, 1yr through importer. Though you are also covered under CGA regardless of who you buy from, but claiming CGA after 1yr through an importer can be more difficult.

But one advantage of buying through an importer is you shouldn't end up with a Telecom branded device.