The first victim received a phone call at her home in Clarence Crescent, Windsor between 3pm and 4pm on Friday.
She was told her card had been used illegally in Habitat and to call the police. She thought she had dialled the 101 police number and was told to hand over her card to a 'courier' who collected it at her door.
But the courier was fake. The fraudsters had kept the victim's phone line open by not hanging up the other end - so that when she dialled the police number she went straight back to them.
The second victim, from Ray Lea Road, Maidenhead was targeted on Saturday at 3.30pm, when a bogus police officer called to say her card had been fraudulently used. Again a fake 'courier' collected the card.
A third person was targeted in Windsor - in Hemwood Road, on Monday. She was called by a man with a heavy Asian accent who said he was a policeman based at Hammersmith called Adam Clarke.
She was also told to phone the police 101 number - but used her mobile to do this instead of the landline, enabling the real police to warn her it was a scam.
Jeffrey Pick, who is the community message co-ordinator for the Windsor and Maidenhead Local Police Area,
is sending out warning leaflets to make people aware of the scam.
He said: "It is so easy to recognise - once you know."
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The victim of an assault in Cippenham was flown to hospital by air ambulance this afternoon.
A rapid response vehicle, an ambulance officer, an air ambulance and an ambulance crew were all called to an address in Earls Lane at 2.10pm.