The Irish Payments Services Organisation said those behind the scam had targeted shops in Dublin last Wednesday, Thursday, and Friday, including pet shops and jewellers.
It is the second time the scam had been carried out, following a spate of attacks in June which left one store thousands of euro out of pocket.
IPSO suspects the same individuals are behind the most recent spate of attacks, which in one case last week led to a shop assistant in a pet store asking customers for their PINs and passing them on.
In last year’s incidents, a man calling himself Mark phoned a number of shops, purporting to be an engineer from their card payment processor (acquiring bank). According to IPSO, he was able to name the correct merchant acquirer and claimed to be a manager, duping shop staff into providing payment card details from sales made at the shop and into refunding numerous payment cards to which he had access.
In last week’s cases, some of the calls were made by a woman and in one case a man called a pet shop, claiming to be from their card acquirer and pretending there was a problem with the terminal.
An IPSO spokesperson said: “He then phoned the merchant every two hours to collect card numbers, expiry dates and PINs for every sale. The merchant asked cardholders for their PIN and wrote those down, along with card details, to give to the caller.
“People who were contacted said he sounded very professional — he duped people who would normally be aware of scams.
“Shop staff seemed to say he is very professional and aware of the workings of the terminals and the tills — and that gave them a false sense of security.”
IPSO believes the card details obtained through the scam are then quickly used to buy online goods which can then by sent to anonymous PO box addresses.
In another case from last week, a butcher was contacted by a woman claiming to be from the shop’s card processor, who then said there were transactions stuck in the terminal which the retailer had tried to send in 2011. However, the butcher had been aware of last year’s scam and did not pass on any information.
IPSO is currently in the process of calculating the approximate amount of money lost in the scam and warned all retailers to verify the details with their own card payment processor.