The banking watchdog has dealt with a 14 percent increase in cases in the past year, with a third of all complaints and inquires dealing with the service offered by banks.
Photo: RNZ
The Banking Ombudsman's office handled 3972 complaints and inquiries in the year to June, up from 3499 the year before.
Ombudsman Nicola Sladden said most cases were resolved immediately and only a few hundred were escalated to a formal investigation every year.
"We've worked hard this year to try and increase our profile so people know about our service, and also making our service easier to use. So we're really pleased that more and people are coming to our service each year for help with our banking issues."
The banking ombudsman scheme has traditionally focused on individual complaints, but was increasingly putting its emphasis on preventing problems occurring, she said.
Lending-related issues accounted for 25 percent of the cases in 2017/18, of which slightly more than half involved property-related lending.