Do not go to the posted coordinates, you will not find the cache there.
BYOP
The shortest distance between 2 points on Earth is called the Great-circle distance (or orthodromic distance or spherical distance). This is the route aircraft generally fly as it is the most efficient way to travel between two points on the globe.
Work out what New Zealand airport (with an IATA code) is the furthest from Dunedin Airport (not including territories and territorial claims - basically within Stewart, South, North and Chatham Islands) . Then work out the Great-circle distance between Dunedin and that airport (there are a number of online calculators to help you with this utilising the airport IATA codes).
Your answer to the nearest kilometre will be ABCD km (note all 4 digits should be different).
The number of letters in the town where the airport located is E.
Add the numeric value for the letters of the IATA code for this airport (where A=1, B=2 etc). The digital root of this answer is F.
The cache can be found at:
S 45° 5C.XYD'
E 170° 1E.ZBF'
X = E - A
Y = B + D
Z = C - B - A
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