One New Zealand-based life insurer has been selling a life product to foreign customers, even though cover was only available to New Zealand residents.
Another insurer incorrectly recorded customers' dates of birth, due to manual errors, resulting in 30 customers being overcharged.
That insurer is now in the process of refunding those affected customers.
Another incorrectly calculated the impact of a consumer price index-linked premium increase by up to 30 times. In all, 223 customers were over-charged.
That problem was discovered in 2015 but the insurer didn't contact those customers, instead relying on them to complain.
Three years after the event, that insurer had failed to remediate 111 of the affected customers.
These are among the examples of issues and poor conduct uncovered by the review of 16 insurance companies by the Financial Markets Authority and the Reserve Bank.
None of the companies responsible for these problems are identified in the report.
The review found examples of insurers failing to cancel old policies when a customer transferred to a new policy and continuing to charge premiums on both policies.
It found insurers which failed to notify policyholders of premium increases.
It found some insurers were selling credit insurance to customers who were potentially ineligible.
And it found examples of insurers continuing to charge premiums on policies that had been cancelled.
One insurer had sent customers mail-outs with incorrect information, which the insurer knew to be incorrect, but took no steps to inform customers they had been sent incorrect information.
This included telling customers of benefit enhancements they weren't entitled to and then subsequently declining claims on the basis of those customers being ineligible.
Another insurer has been charging such high premiums for funeral insurance that the amount of premiums was more than the sum insured. That insurer only remediated customers who complained.
The report says that the New Zealand arms of the Australian companies identified by Australia's royal commission into financial services as being responsible for various types of misconduct, such as charging for services never delivered, have said they are confident such problems are unlikely to be occurring in New Zealand.
"We consider this confidence is misplaced. Overall, insurers did not know enough about what issues may exist in their business and there was insufficient effort made to discover them," the report says.
Fewer than half the insurers had undertaken some form of analysis by the end of the current review.
The joint statement from the FMA and Reserve Bank says "it is not appropriate to name or attribute findings to any individual firms.
"While there are follow-up inquiries into specific issues, the regulators will not be commenting on the nature or identity of these inquiries. When the process is complete and in the event that misconduct is discovered, particular firms could be named as a result."
The FMA took the same approach to a review it released in July when it said three of the 11 life insurance companies were responsible for behaviour so bad that it was considering taking regulatory action against them.
It turns out that after follow-up inquiries, the FMA decided further action was unwarranted.
"At the time, the FMA was criticised in some sections of the media for failing to name those insurance companies," the FMA says in response to BusinessDesk's inquiry about what had actually happened.
"The outcome in this case highlights why the FMA does not name entities it may be making inquiries of until further investigation has been carried out off the back of thematic reports," it says.
"Concerns and further inquiries do not mean that a business has committed wrongdoing."
However, by failing to name the three potential transgressors, the FMA had effectively tarred all 11 companies – which were named – with the same brush.