I've seen a few commenters on Geekzone saying class action type suits are not possible in NZ so I wonder about the difference there. It also says the justice minister is working on changes to make class actions easier.
I might be due for about $20 over the last six years. Not looking forward to checking my statements lol : )
Edit: Stuff published a history of recent class actions in Australia which had an impact on NZ late fees: "Westpac, for example, cut exception fees on all credit card and accounts from $25-$30 to $9, a move that cost it about $50m each year. While most default fees now fall in reasonable ranges, the class action is expected to extend back six years, the maximum length of time for a claim under the statute of limitations"