Phone scammers pocketed more than £55,000 by tricking their victims in Northamptonshire during 2019.
Police say most of the victims of what they call "courier fraud" are usually elderly and are tricked by fraudsters targeting victims claiming to be from their bank or even the police.
Conmen usually phone their victims and persuade them to reveal their PIN number, bank or credit card and other personal details.
But Northamptonshire Police's Fraud Team managed to arrest one brazen scammer who turned up in person to collect more than £6,000 in cash.
Detective Inspector Tania Ash, said: “These scams can be very sophisticated and can result in devastating losses of tens of thousands of pounds.
“Often, vulnerable victims are sworn to secrecy or made to feel that there are severe consequences to others or their finances if they tell anyone what’s going on.
"They are sometimes visited by criminals in their own homes and when they finally realise they have been scammed, they often undeservedly feel a great shame.
“The people carrying out these scams are exceptionally clever and know how to manipulate their victims by making them feel panicked and rushed."
Nationally, around £6.5million was stolen last year using the sort of scams highlighted in Channel Five's TV drama Cold Call last year. The victim, played by Sally Lindsay, was ricked ino transferring £83,000 from her bank account by a conman pretending to be from her bank.
Northamptonshire Police were alerted to one scam by the victim's bank after he was encouraged to take out over £6,000 by someone claiming to be selling solar-powered technology.
The fraudster drove the elderly man to a bank to withdraw the money. However, suspicious bank staff called the police who arrested a man on suspicion of fraud in connection with the incident.
Det Insp Ash added: "This is a great example of how the banks can work with us to challenge potential incidents of fraud.
"Instead of this man losing several thousand pounds, a man was arrested for attempting to defraud him.”
Detectives want the Northamptonshire public to make elderly friends and relatives aware of the tricks conmen use.
Det Insp Ash added: “Please remind them that a police officer or bank staff member will never ask for your PIN or personal details or arrange collection of your bank card -- nor ask you to withdraw cash to send for examination.
“Your bank, the police and any genuine organisation will never contact you and ask for your online banking log in details, including a one-time password, or to move money to another account.
"A genuine member of either organisation will also have no issue with a person putting the phone down and ringing 101 or the bank to establish their true identity.
"If you receive one of these calls, end it immediately and contact the police and your bank via a different phone line, using a number you have verified. If you do not have another phone line you can use, hang up and wait five minutes until the line has fully cleared."