Vulnerable shoppers are being targeted by unscrupulous gangs of thieves who pretend to be good Samaritans in order to steal their bank cards.
A customer at Sainsbury's in Canterbury was one of the victims of a spate of "distraction thefts" to hit east Kent in the past month.
The incident in the car park of the store in Kingsmead Road on Thursday, March 6, was one of seven thefts to take place at Sainsbury's and Waitrose stores in Canterbury, Ashford, New Romney and Hythe.
Shoppers are now being warned to be on their guard against gangs of criminals who work as a team to carry out the thefts.
One method they use is distracting shoppers at their cars, by telling them one of their tyres has been punctured by a nail.
When the victim bends down to inspect the tyre, an unseen accomplice takes their bank card from the car or shopping trolley and makes a quick exit before arousing suspicion.
Another tactic is telling the victim they have dropped some money. The bogus good Samaritan then hands over some change to divert their attention away from an accomplice picking their pockets.
One of the gang members has usually already stood close to their target at the checkout and taken note of the PIN they have entered into the card machine.
It is usually much later when the victim gets home that they notice their bank card missing.
Detective Chief Inspector Emma Banks says: "There are no set patterns and nothing to suggest these incidents are linked. We believe different offenders are responsible using a tried and tested distraction technique.
"The distraction works because it is human nature to take these strangers at face value, especially when they appear to be offering helpful information such as ‘your tyre has a puncture’ or ‘you have dropped some money’.
"My advice is to treat such approaches with caution and to take care to put your shopping away and keep your purse safe, and lock items inside the car if possible, before you engage with the stranger.
"If you do engage with them, beware of anyone who might be hanging around and don’t be afraid to lose eye contact with the person who is trying to get your attention, to check what’s going on around you."
She adds: "Take care when entering your PIN number in the supermarket - use one hand to conceal view of the keypad from other people.
"If you are suspicious about anyone approaching you, stay calm, keep your belongings safe, and either report the incident to the shop or call Kent Police."
Anyone with information is asked to contact Kent Police on 101 or Crimestoppers anonymously on 0800 555 111.