A woman had €9,500 taken from her account after she responded to a scam email purporting to be from her bank.
The woman, named Carmel, hit out at the bank's treatment of her and said she intends reporting it to the Financial Ombudsman.
Carmel fell victim to the fraud in February after she responded to an email that appeared to be from Bank of Ireland.
She has not yet received any refund from the bank.
Speaking on RTE Radio One's Liveline, she said she could understand why people would say she should have been more careful.
"If this was €100 or €200 you'd say 'fair enough'," she said.
"Given that it's a substantial figure, I suppose I was expect- ing a completely different outcome."
The problem first arose when Carmel responded to an email, which said the bank wanted to update her account details.
She was then prompted to put her name and her mother's maiden name in a pop-up box, which she did. She told listeners she was not asked for her password or other security details.
She was then alerted to a number of transactions via the bank's text and email service, and learned that her account had been emptied in the space of an hour.
"What came back to me was that I had revealed sufficient information to allow the scammers to be able to use the data to withdraw the money," she said.
She added that she had the large sum in her account as she had just changed her car.
The bank later told her that as she had revealed the information, it could do nothing about it. That decision did not change after she made a complaint.
While Carmel admitted that the bank alerted her to the problem, she said the procedure "would lead you to believe if they alerted you they would do something about it".
She said she thought that telling the bank she had revealed her information in response to the email had reduced her chances of getting her money refunded.
"I'm a customer for 20 years plus," she said. "I have all of my banking with them. I have my mortgage with them. They are making more than the money lost from the interest on my mortgage," she said.
Carmel also expressed her dismay at not receiving a phone call from the bank, and dealing only through letters.
"My next step is the Financial Ombudsman," she said. "That seems to be as much as I can do. For such a substantial amount, I would have imagined a phone call at least."
Bank of Ireland said its customers are always advised not to reply to suspicious emails, pop-ups or webpages or follow instructions they give.