A) In the interest of diversification I've been exploring other markets and ANZ holdings, a New Zealand bank

ANZ Bank ("Australia New Zealand Bank") is not a Kiwi bank, but as their name says a Australian & NZ bank. In NZ (probably/maybe in Aussie too) it's the largest one, followed by BNZ Bank.

B) They seem to have a bad reputation with their customers
Not in NZ. I was their customer in the 90s, my Ex is their customer since 2015. All good apart from once when she transferred money from Germany into her ANZ account being heavily overcharged by them using a 2% too low exchange rate. We complained to the Banking Ombudsman and ANZ quickly caved in, crediting 1.5% or so of those 2%.

This alone btw is not anything giving ANZ a worse reputation than any other bank, as they all have that "habit". Next year we did it the other way around, letting her German "comdirect" bank exchange the EUR into the then into her ANZ account transferred NZD. comdirect", daughter of one of Germany´s oldest and most reputable bank, overcharged (additional to their fees) even by a 2.2% lower exchange rate than the then exchange current rate of the ECD (European Central Bank) --- and our complaint at the German Banking Ombudsman, proofing the overcharging with detailed numbers and calculations, was greeted with a standardised reply essentially saying "... contract between comdirect and customers allows comdirect to use any exchange rate"). It was clear proof who the German Ombudsman works for and is paid by (the banks, not the customers).

C) In the interest of diversification I again have money in NZ. This time at BNZ bank, but only because my Ex (still good friends) as said has an ANZ account = to also diversify between banks. Otherwise I would without hesitation had an ANZ account.