Bank customers have received nearly $39 million in compensation since the Banking Ombudsman scheme began operating 25 years ago.
But the scheme nearly got pulled at the beginning after two banks threatened to withdraw their membership.
"There were rocky moments in those early days," says current ombudsman Nicola Sladden.
Despite being originally set up by the New Zealand Bankers Association she says some of the members found it hard to cope with the early decisions.
"They struggled to get past their indignation at being held to account."
Fortunately, Sladden says, today the banks have a far more supportive attitude.
In the first year the service handled 348 complaints. That has now grown to over 3000 cases a year.
Over 78,000 people have made complaints since it started.
Types of complaints have also changed dramatically.
Back in 1992 cheques and passbooks were the main areas of concern but along with technological change the service has seen a rise in complaints about online payment issues.
In recent years there has also been an increase in complaints around online scams and fraud.
Sladden said those cases could be particularly sad and there were often two victims - both the banking customer and the bank.
Solving the dispute came down to working out who was going to wear the loss.
"It is scary stuff. It could happen to any one of us."
That was why it was important for the banks and customers to be scam savvy.
Sladden, who is the fourth Ombudsman for the scheme and has been in the role for two years, says complaints relating to property are also a common theme.
Last year it had a run on people complaining about fees when they tried to break the term of their fixed mortgage to switch to a lower rate.
It has also had complaints relating to changes in payment processing times with the banks moving to real time banking.
From the banking side she has seen slight increase in banks exiting customers - the official term for when a bank says they will close down a person's accounts and no longer provide them with a service.
This can be because of threatening and abusive behaviour towards bank staff.
Then there are the quirky cases - she remembers one where a woman complained that she had banked $1000 through an ATM but only $660 of it went into her account.
The bank said its machine had very comprehensive systems in place to count money and claimed the woman must have banked less than what she said.
In the end the ATM maintenance guy turned out to be the hero when he found the money jammed in the machine in a routine check-up.
Sladden was also once offered a slab of venison by a Gisborne man who was grateful for the scheme's help after a run in with his bank.
She politely declined.
While the nature of complaints is continually changing Sladden says people remain at the heart of banking and people make mistakes.
Even with the advent of robo-advice around the corner there will always be people involved and therefore a need for a dispute resolution service, she says.
Banking Ombudsman Scheme - 25 years on
• established in July 1992 by the New Zealand Bankers' Association - driven by its then chairman Sir John Anderson with support from then Consumer NZ chief executive David Russell
• has paid out $38.99 million over 25 years.
• helped 78,000 people
• has 19 members including the four largest banks - ANZ, ASB, BNZ and Westpac
• can award a maximum of $200k per person in compensation