gnfb: Getting int the area of "i don't have a clue what I am talking about!"
Can you buy a plug for a new Zealand socket that one would install oneself that has a fuse in it? her in new zealand?
The mains cable, plug, and fuse system are rated for 10A. If you change the plug it will just blow the fuse. If you change the fuse there's a (small) risk the cable overheats and causes a fire. If could be expensive to get working if you do it properly, the costs could far outweigh the savings even over many years.
All in all strongly suggest you don't use it.