The Banking Ombudsman scheme has investigated a record number complaints and disputes.
In the past financial year, a record 715 investigations were carried out.
Ombudsman Deborah Battell says the amount of investigations is more than double the number done in the previous year.
Mrs Battell says the office facilitated the return of $14.5 million to customers, including about $13.8 million to ANZ customers who had invested in an ING scheme.
The ING investigations comprised about half of the total work.
Ms Battell says she expects between about 400 and 500 investigations to be conducted this financial year.