Forget the details but I think the runways to short (or some performance issue) for Air NZ Link to have ever gone in there (Greymouth).
I think til recently there was no IFR approach into Greymouth, being a lack of NDB/VOR. GPS Approach a recent addition.
Air West Coast I believe used to IFR it to Westport then VFR it down the coast to Greymouth, not a flash practice at night and/or in the ****e weather.