International scammers are running large, slick operations to raid bank accounts.
The country's largest bank, ANZ, says the number of attempted scams it has dealt with this year has more than tripled, compared with last year.
It says it's never known so many before.
The biggest increase is in the number of scammers calling people to tell them their computer is faulty and they need to make a money transfer.
ANZ chief operations officer Mike Bullock said the people involved are big international businesses that hire experts to impersonate representatives of trusted companies.
Mr Bullock said while they try to recover any money stolen, often they cannot - and that can be heartbreaking, especially at this time of year, for those defrauded.
He said the bank's fraud teams are continuing to investigate claims right up to Christmas.
