SBS Bank has been labelled "heartless" after refusing to refund $134,000 siphoned by thieves from a pensioner's online accounts, saying the recent heart attack victim failed to take adequate precautions.

The distraught man is recovering from triple heart bypass surgery which he believes is linked to stress from being swindled.

He says he has been rocked by SBS's decision and the bank's hardline stance is ironic given it advertises as "putting the heart back into banking".

However, SBS, which recorded a $61 million operating surplus last financial year, says the matter is now closed and the man is free to complain to the Banking Ombudsman.

The Herald reported last month that cyber criminals had "hacked" the man's accounts then used a secure messaging function to contact bank staff, posing as the man, and changed his cellphone number to circumvent SBS's two-factor authentication security checks.

They then added several new payees before moving large amounts of money to six different accounts at four separate banks in 11 transactions over five days.

The man, from Invercargill, learned the money had been taken only when he logged in to his internet banking on July 20 to pay bills and found his revolving mortgage account had been drained to its $134,000 limit.

Police sought court orders to force SBS and the other banks to hand over details of the recipient account holders in a bid to track the money.

However expert warn the account holders may only have been "mules" and the money is likely long gone. It's understood no arrests have been made.

A letter from SBS last week titled "Fraudulent Transactions Complaint Outcome" confirmed the bank would not be refunding the man's stolen cash.

The letter said SBS was sorry to hear about the man's recent health issues, which had impacted staff's ability to fully investigate the theft.

"We would have liked to spend further time discussing this matter with you to try and understand how access to your internet banking has been achieved by another person.

"Based on the information we have at this time; our finding is that the bank is not liable to refund you for the loss."

The bank cited a delay in the man checking his accounts and informing staff of the fraud, resulting in the funds being "not recoverable".

It also claimed the man disclosed having a "notebook that contains various passwords and user names for various online accounts you hold".

"We have not been able to view and ascertain whether it contains your SBS password information, or that you don't use a generic password for multiple online accounts including SBS Bank."

The letter noted that the man's internet banking was accessed successfully on the first log in attempt, suggesting the person knew the victim's password.

It also said the man had recently purchased a vintage motor vehicle, and that "many of the fraudulent transactions were referenced as "Car".

"Based on the above information we have concluded that you have not taken sufficient steps to protect your banking adequately."

SBS appreciated "this will be a disappointing outcome for you" but noted its letter was a "final response".

The man said the bank's stance was heartless and unfair.

He'd suffered a "breakdown" after receiving the letter and was in tears on the phone to the Herald.

The former business owner was adamant he had not shared his online banking password with anyone, or provided personal information in response to phishing emails, phone calls or texts.

He believed SBS's security systems had failed.

While he did have a notebook containing some passwords, he said none related to SBS, and they were all different from those used for his online banking.

In the man's opinion, his treatment by the bank was disappointing and "bloody awful".

"They have these ads, 'The bank with a heart'. F***ing heartless."

The man said he was part of a generation who were not particularly computer savvy and online banking had been imposed on them by banks.

"They forced it on us so they should be a bit more responsible. I still don't think their bloody systems are good enough."

The Herald asked SBS how it could be certain the man was at fault and refuse to take any responsibility for the stolen money.

The bank said it took the complaint seriously. It had conducted its own thorough internal investigation and advised the man of the outcome, "based on the information we were able to obtain".

Police were now investigating the fraud as a criminal matter. SBS said it was assisting police with their investigations.

"We appreciate that this will be a disappointing outcome for [the victim] and as his complaint is still in dispute, we have advised that he would be best to request an investigation via the Banking Ombudsman Scheme."

Banking Ombudsman Nicola Sladden said her office could now commence a formal investigation should the man wish to pursue his complaint.