ACC bank hired a private investigator to snoop on a separated couple who owed more than €900,000 to make sure they were not living a "lavish" lifestyle.
In a report for the bank seen by the Sunday Independent, the private investigation firm checked up on their family home and lifestyle by conducting "discreet inquiries" with the neighbours.
The PI spoke to local residents to find out what kind of cars the couple drove and whether they went out a lot. The report included photographs of the family home where the separated woman lives with her adult children, and photographs of her former husband's house in another area.
"At the time of our agent's visit to the area... it was noted that there was a Toyota Avensis parked on the driveway of the property. Our agent was informed by local residents that this is believed to be the only vehicle to which (the woman) currently has access," the report said.
"Due to the layout of the property and the position in which this vehicle was parked, it was not possible to establish the registration number of this vehicle."
The private detective also established from talking to neighbours that her ex-husband drove "a black 4X4" but couldn't manage to get its "make, model or year of registration".
"During the course of our inquiries we were informed that [the separated couple] appear to be leading a quiet life and show no signs of a lavish lifestyle in any way."
According to internal bank email, the private investigation firm quoted ACC an initial fee of €3,500, a monthly fee of €150 and a "disposal fee" of €1,000 for the report which was carried out in 2014.
However ACC Bank said such reports usually cost an average of €500 and are paid for by the bank, not the customer.
The woman who was subjected to this surveillance was unaware she was being spied on until she sought her records from ACC Bank under the Data Protection Act.
"I was shocked at the thought that there were detectives prying around my house, taking photographs and talking to neighbours about me," said the woman, who asked not to be named.
"It was intimidating. I had done nothing wrong. They had everything they needed to know about me at that stage."
She is in dispute with the bank over debt, which relates to a mortgage loan taken out by her ex-husband on a commercial property in the South.
A statement from ACC said from time to time, it "commissions legitimate private investigators to assist with obtaining information in relation to clients in arrears where we are unsure that we are getting full disclosure of income/assets. This is consistent with industry practice and the information is retained in compliance with data protection legislation. The standard cost for such reports is circa €500. Any costs incurred are borne by the bank."
Banks are increasingly relying on detective agencies to probe debtors - but usually for "high net worth" clients who claim they cannot repay their loans.
David Hall, of the Irish Mortgage Holders Organisation, said that those who owe more modest sums don't escape snooping bankers either. He said banks are also scouring Facebook pages of customers in debt for evidence of expensive holidays, fine dining or businesses they don't know about.
"No one likes being spied on," he said.