An alert assistant at Ridgewood Post Office stopped fraudsters from conning money from the business on Saturday, October 31.
Later the same day, the same trick was successful in a High Street business where £100 was stolen.
Wealden police are now warning retailers to be on their guard.
‘Ringing the changes’
The incidents involved a type of fraud often called ‘ringing the changes’, where someone asks for a sum of money to be changed into notes of a smaller denomination.
While the cashier or shop assistant is doing this, the trickster deliberately confuses them in order to obtain more money than they handed over in the first place.
Sussex Police said just before 1pm on Saturday, October 31, two men entered the Post Office in Lewes Road, Uckfield, but the assistant realised what was happening and they left empty-handed.
Police issue descriptions
One of the men was described as white, with an eastern European accent, in his mid to late 20s, of stocky build and wearing a hat and a grey/blue fleece.
The second man was similar in terms of age and accent, but he had a tanned appearance and was wearing a blue bandana and a grey/blue fleece.
The second incident happened later the same day at a business off the High Street, Uckfield. At around 10.30pm two women managed to obtain more than £100.
One of the women was described as 20-30 years-old, of eastern European appearance, with brown hair and a slim build, wearing a white top and jeans.
Advice to businesses and retailers
Her companion was a 35 to 40-year-old woman, with brown hair, wearing tracksuit bottoms and a hooded top.
Sergeant Kara Tombling said: “I would like to advise businesses and retailers to be very cautious if they are asked to exchange notes for lower denominations, and if they are in any doubt, to refuse the request.
“As the festive season approaches, shops and businesses will be getting busier, so extra vigilance is needed and counter staff need to be made aware of this scam, which can prove to be very costly.”