Last I knew, the China Southern flight school in WA had quite a few kiwi instructors. But even that probably won't help...
Just to do the BFR:
A. The instructor must be B category or higher
B. Their NZ instructor rating must be current
C. They must be able/ willing to fly with you outside of their employment contract
D. I have been told, but cant confirm, that an NZ BFR can only be flown in a ZK- registered aircraft
E. So then you need to find a ZK- aircraft which the owner is willing to hire out to a student and instructor whom they probably don't know...
As for the SEIR renewal, you'll need a flight examiner for that. And they're often hard enough to source at home in NZ!
Good luck, and enjoy your trip to New Zealand!