Wot padmei sed! 
You could try my son-in-law Rudy, Europlumbing Ltd. He's landing back tomorrow morning from overseas, but if he's not available speak to Paul he's the co-owner and runs the day to day business. 09-550 6202 Can't promise as they haven't said they're looking for anyone, but worth a try.
They do all the aspects, from basic plumbing repairs and maintenance to design and build new, refurbishing/restorations and drainage as well as design and build solar installations for all types including pool heating. A mix of domestic/residential and major commercial jobs in multi-storey buildings.
You've got a good head and are asking the right questions, so all the best!
You don't get to be an old dog without learning a few tricks.
Shorai Powersports batteries are very trick!
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