The Banking Ombudsman's office is dealing with a sharp rise in new disputes, mostly due to a jump in complaints about mortgage defaults.
The number of disputes the office has on its books rose 73% in the five months to the end of November, compared with the same period last year.
Banking Ombudsman Deborah Battell says lending problems, especially mortgage defaults, are the main cause of the increase as banks toughen up on their worst defaults.
She says the cases she sees are often at a point that properties are about to be sold by mortgagee sale.
Ms Battell says complainants make a variety of allegations such as that banks should not have lent to them in the first place, or that the bank is pushing them into a mortgagee sale when they think they can continue to pay and want to stay in their house.
Ms Battell says those at the office wrongly expected the number of new disputes to reduce this year because it was thought the major effects of the global financial crisis had flowed through.
She says the office now expects the dispute levels to remain high next year.