It is a scam being undertaken through the post by a German company called Corporate Portal New Zealand.
Do not respond to any correspondence from this company.
A quick link to full details of this scam are listed on the Commence Commission New Zealand website.
http://www.comcom.govt.nz/the-commission/media-centre/media-releases/detail/2015/small-businesses-targeted-by-corporate-portal-invoicing-scam
Author: Sue Granger