My advice would be:

Join www.oldfriends.co.nz for free and look up people with the last name LATOA. you will find 25 people with that last name, 19 of which live in Auckland.

by joining the oldfriends site you will beable to e-mail all those 25 people and ask if they know of anyone called John LATOA, maybe best not to mention why, as you may not get any replys.

Or go to www.whitepages.co.nz and ring people with that last name in the Auckland area.