They bought the gift for a child without knowing what was inside.
His mum says she's had her "faith restored in humanity".
NZ Post defended the move, saying there's nothing to be concerned about.
The Privacy Commissioner has ruled it breached the Privacy Act.
His alleged attackers also stole more $800 from him.
Hundreds of thousands of parcels are still waiting to be delivered, with Christmas fast approaching.
Govt-owned NZ Post is to cut 500 jobs over the next three months in an effort to save $50 million.
New Zealand Post has announced a six month after tax profit of $110 million. But it has voiced fresh concern about its mail and parcels business.