This is a bit of a problem, have you tried a hard reset - beware this will erase all user data from the phone (pictures texts etc)!!
Turn the Power off
Press and hold the Volume down, Power, and Camera buttons.
When the Phone vibrates, release the Power button, but keep the Volume down and Camerabuttons held for a few more seconds.
Also does the phone actually work when plugged in? have you tried a different charger etc?
further than that I dont believe there is a official service agent in chch it would have to be sent to auckland, and if the phone is out of warranty for the price of repair it might be just as easy/cheap to replace it with a lumia 52x-72x