"The quality of Radio NZ's service will be compromised for a minor monetary gain at a time when the broadcaster says audiences are at an all-time high"
Nonsense. If you are worried about the quality of Radio NZ's service (a subjective measure, but I'll leave it to you), then you CAN do something about it.
Donate money to Radio NZ.
Not used to paying for things you like? You should be. It's what you do if you subscribe to Sky TV, or buy books and magazines, go to the movies etc. Why is this any different?
Stop wanting to bludge off of other taxpayers for your own personal choice. If audiences are at an all time high then great. You too can set up a campaign to support Radio NZ.
Seems a bit hard? Well you might learn something. Businesses don't (typically) get handouts to start up, neither do charities.
Or would you rather spend your money on dessert, a bottle of wine, a holiday, some CDs you like? Because when it comes down to it, you only care enough about Radio NZ to lobby the state to make others pay for it.