Hi Mother Bear.
The first mistake I made was sending it to the officer I was dealing with over the telephone and previously with the ex's RRV. I should have sent it to the main processing office and then they deal with it as a new application. Secondly, I wrote both the physical address as well as the post box address on the envelope - as you would see on their letter heads; apparently it should always be the just the post box address.
Immigration are not sure whether it is floating around their office, in transit between offices, or the postie made a mistake ... so NZ post are investigating as well.
Just in case of the worst scenario I think I had better now go and find out how long and costly having the passports replaced will be.
