An ANZ spokesman said it was disappointed the customer's query wasn't managed in a reasonable time.
"We sincerely apologise to the customer and hope their query was resolved satisfactorily."
The ANZ situation follows that of the ASB which confirmed it has been experiencing an "unprecedented increase" in dispute inquiries in recent months.
An ASB customer was last week told he would have to wait at least a month to have a fraudulent transaction dealt with because of the increase.
In an email the man was told: "Due to the unprecedented increase in dispute enquiries we apologise for the delay in responding to your enquiry.
"We will endeavour to have your enquiry actioned by 25 May 2018."
The customer found out about the fraudulent transaction on April 24.
An ASB spokeswoman said the bank had been experiencing a steady increase in disputed transactions over the past few months and put it down to the rise in online activity.
"The recent increase is due to a number of reasons, driven mainly by an increase in the volume of online transactions, as more people embrace making digital and online purchases."
The spokeswoman said with online purchases it meant fraudsters were ever present, increasing the level of risk, some of which were very complex and took time to investigate.
As well as more fraudulent transactions the bank was seeing more customers disputing charges for transactions like online games, subscriptions they were not aware of, or when a free subscription time had expired and the customer had been caught out.
The ANZ spokesman said it had seen a steady increase in dispute and potential fraud queries over the past 12 months - as had been the case in previous years.
"The reason is that more customers are shopping and gaming online at international websites."
The ANZ said it had recently increased resources in those areas and continued to invest in fraud monitoring technology.
Both banks urged customers to step up their own vigilance.
"ANZ recommends customers research the companies they are buying from overseas.
"Customers should ensure they read the fine print on free trials and subscriptions and be aware of lending devices to people which have card details stored to purchase online games.
"Customers should also be alert to phishing attacks and avoid responding to SMS or email messages purporting to be from their bank, or other trusted entity."
Other banks said they had not seen a recent spike in fraud or dispute inquiries.
A spokeswoman for Kiwibank said it had not experienced a dramatic increase in dispute inquiries over the past few months but like all banks it had seen significant growth in online card transactions.
"And with that growth we have seen increases in disputed and unauthorised transactions. With this in view Kiwibank is constantly working to lift expertise in this area so impacts on customers are minimised."
The spokeswoman said like ASB, it had more customers disputing charges for transactions like online games, subscriptions they were not aware of, or when a free subscription time had expired and the customer had been caught out.
She said about 30 per cent of disputes related to what a customer recalled, often due to the merchant name not matching the store front; subscription confusion; and a general lack of awareness around online charges.
A Westpac spokeswoman said it had not seen an increase in exposure to this type of fraud at Westpac.
"We use a sophisticated set of tools to assess and block high-risk online transactions.
"We also monitor internet banking and regularly update our monitoring and detection criteria in response to emerging fraud patterns that we detect so that we can protect our customers and the bank."
BNZ said it too had not seen any increase in dispute inquiries.
