Police are warning residents to be careful when paying at car park meters in town, after a woman in her 80s lost £980 in an incident on Talbot Road Car Park in Rickmansworth on April 6.
The elderly woman was approached by a male when paying for her parking near the high street last month.
The man asked for help with payment, claiming that he only had cash and could not pay for his parking as the new metres are card only.
The lady offered to pay for his parking and lost two bank cards after putting them into the machine.
Two unauthorised transactions of £480 and £500 were later made from her account.
The lady has now been reimbursed by her bank for the theft.
Police believe the stranger could have taken the cards directly from the machine using sleight of hand after watching her type her PIN or may have used a device to trap the cards.
Alan Waller, Rickmansworth Police Community Support Officer said: “Our advice is, do not offer to pay for somebody else after they have approached you, however genuine they might seem.
“Do shield the keypad terminal with your other hand when typing in your pin number to pay for parking. If you feel uncomfortable about anyone approaching you like this then please call the police on 101. Please inform friends and relatives about this scam.”
Hertfordshire residents can sign up to receive alerts on crime in their local area at owl.co.uk