Just another update: still no response, I have widened my efforts by makeing a formal complaint to the commerce commission on the basis that the the web-site is in breech of the False Advertising rules, while the logo on the packets is Misleading (other exotic flowers have a different logo).
I have also written to the Ministers of Conservation and Environment. The latter, Amy Adams, member for Selwyn (or a staffer on her behalf) considers it a matter for the Minister of Conservation. Unfortunately DOC has no weed jurisdiction outside Conservation lands. Happily a better response from Dr Nick Smith's office, to whom I passed on the sponsorship suggestion as well.
Sonya, I think ERMA regulate new organisms but if it is here already and not on the National Plant Pest Accord list or the local authorities lists, anything goes.