Suburbs boundaries in New Zealand

I am quite interested to get the suburbs boundary of different regions of New Zealand, Australia, and Fiji. I fetched the data from here using the id: Relation: Waikato (2094142) and http://polygons.openstreetmap.fr/get_geojson.py?id=2094142&params=0 Unfortunately, I could not find the region boundary for North Shore in New Zealand on OSM.

I would like to know the way using which I can obtain the regions, districts, and, suburbs boundary data (Type: MultiPolygon)for any country.