The bogus scam has been noted around the country - but has recently been reported in and around Dinnington.
Independent IT consultant Chris Guest said: “I have customers all around the area - from Aston, Retford and Worksop, and I’ve had a number of people calling and saying that they’ve been targeted.”
“You get a cold-call out of the blue from people claiming to be from Microsoft and they say that they are monitoring a virus on your computer.”
He continued: “They then try to convince you to let them remotely control your computer so they can clean up the problems.”
Chris added: “Once they are done, they ask for your credit card details and £150 - £200.”
One person who was targeted by the cold-calling con-men was Julie Bradwell from Worksop Road in Aston - now she wants to warn others to not fall into the trap.
“It felt dreadful,” said Julie. “It sent me into a complete panic.”
“It sounded like one of those cold callers with an Indian accent. At first I said I didn’t want to talk to them and I put the phone down, then they rang me back which is really unusual, then asked me to turn on my computer.”
She continued: “Then they asked me to turn on my computer because they said it was corrupt and downloading a lot of files that were about to crash and ruin my PC.”
The voice on the phone then asked Julie to press a series buttons which allowed them to remotely control the machine and reveal error messages.
Julie went on: “Eventually, they got to the bottom line and said they wanted £199 to clean my computer. At that point I told them I didn’t have any money and that I’d just throw the computer away.”
“Then they asked me how much I could afford, which was really strange. I just said I only had £20 and they said they could clean up my computer for £39.99. I gave them my credit card number and they did something to my machine, but soon after found out that it was all a con so I blocked the transacation and cancelled my card altogether.”
She added: “They were totally convincing and I feel like an absolute fool. I should have done more checking and I strongly advise others to do the same, or just hang up and ignore them.
A police spokesman said: “There is a real warning here about internet security.”
He added: “Do not reveal personal financial information to anyone whose identity you cannot verify and trust.”
If anyone has any information about a similar incident, you can report it to South Yorks Police on 101 or you can contact Crimestoppers anonymously on 0800 555 111.