SINGAPORE - The customer wanted to withdraw $10,000 from her bank account, but something was wrong.
When staff at POSB's Woodlands branch tried to make small talk with her, she was silent. Instead, she wrote on a piece of paper: "My son has been kidnapped."
Branch service manager Kina Neo, 50, said of the encounter last November: "She looked like she wanted to cry."
Ms Neo took the woman, a fruit seller in her 40s, to a private room and kept communicating with her through writing. The woman revealed that she had answered a phone call and heard what she thought was her teenage son's voice begging for help.
422 Scam attempts reported last year
40 Successful scams last year
This was followed by another caller demanding $10,000 if she wanted to see her son again. She was ordered not to hang up so the caller could listen in on whatever she was doing.
On learning that the customer's son was doing his national service, Ms Neo managed to get in touch with his officer-in-charge and ascertain he was still in camp.
The phone call had been nothing more than a hoax.
Such kidnap scams tripled in 2014 from the year before. The police received 422 reports of such scam attempts last year, 40 of which were successful - compared with 13 out of the 178 reported in 2013.
These scams usually involve the victims getting a call from someone pretending to be their relative in distress. A "kidnapper" then comes on the line and demands that they remit a ransom, usually to an overseas bank account.
In the first half of this year, 241 scam attempts had already been reported, up from 216 in the same period last year.
Of these, 22 victims were cheated of a total of $98,100, close to the $113,700 lost across the 40 cases last year. The highest sum handed over in a single incident last year was $45,000 in January.
Ms Neo said she has stopped three such scams from happening to bank customers.
"When staff spot unusual customer transactions, any red flags, they will highlight it to me or my assistant," she said.
A police spokesman, in a warning, advised the public against transferring money to such callers, and to contact their loved ones at once to confirm their safety.
They should report these cases to the police immediately, he added.
He said: "To avoid becoming a victim of this scam, remain calm and ask the caller to identify the kidnapped person."
Technical officer Siok Siew Hua, 62, did just that when he received such a call from someone claiming to be his 21-year-old son last June.
Mr Siok recalled: "He was crying, 'Papa, come save me, they have caught me!' I almost believed him, because my son was doing military training in Thailand at the time, but I kept calm and asked what his name was. The guy just hung up.
"It sounded like my son because he was half-crying, so I couldn't really hear his voice."
Ms Neo, who has been the subject of such calls herself, said: "Normally, the customers are really afraid and, in their panic, they think it has to be their children crying for help."
In the case of housewife Tan Ah Moi, 72, a scam attempt in June this year backfired because her distress was too great.
Hearing what she thought was her granddaughter, 23, screaming for help over the phone, she panicked and accidentally hung up before the "kidnapper" could demand a ransom.
Unable to call back on the same number, she and her husband, 81, ran out of the house in their pyjamas and hailed a cab to rush to their daughter's place. When they arrived, they were confused to discover their granddaughter safely ensconced in her room.
Madam Tan said in Mandarin: "If I hadn't hung up, they could have lured me to goodness knows where, or taken any sum of money from me. All I could think of was saving my granddaughter."