Scammers targeted nine people in just one day trying to trick them out of money.
The con artists posed as police officers or bank staff and asked for bank and card details.
Five residents in Brighton and four in Bognor were targeted in just one day on April 16.
In eight cases the residents became suspicious and did not part with any information or money.
But in the ninth case a woman in Brighton gave her bank and card details and handed her cards over to a courier at the door, together with £200 cash.
Police were informed and the cards were cancelled before they could be used.
It follows a recent rise in this type of crime across Sussex.
Police are urging residents to be extra vigilant, especially the elderly or those who live alone.
The fraudsters call the intended victim claiming to be from either the police or a bank.
They tell them their card details have been fraudulently used and they need to act urgently to protect themselves.
They suggest they hang up and ring the bank or police back to ensure the call is genuine.
But then they stay on the line and pretend to be the police or the bank.
They will then send a taxi or courier, who may know nothing about the crime, to collect the bank card.
With this and the PIN they will then have full access to spend your money.
Detective Inspector Jim McKnight said: “Under no circumstances would the police or your bank request your PIN over the telephone or arrange collection of your bank cards from your home address in this manner.
“Never give out your bank details to someone who has contacted you on your home phone unsolicited. If you have any suspicions please do not use the phone you have just been called on to contact the police or your bank.
“If you have any information, whether you have received similar calls or know someone who has been a victim of this crime, contact Sussex Police via 101 or email email@example.com quoting Operation Edisto. You can also call the independent charity Crimestoppers anonymously on 0800 555 111.”