Police in Devon are warning people about the latest scam which has seen some victims conned out of thousands of pounds.
It's known as the Microsoft Tech Scam - or Computer Software Service Fraud - and involves call centres cold calling victims claiming to be from legitimate businesses like Microsoft.
The caller says that there is an issue with the victim's computer which they offer to fix for a fee.
Devon and Cornwall Police say typical losses are around £200 but there have been instances of some victims being subjected to repeat victimisation, leading to large losses.
In one instance a victim lost more than £70,000.
This can be due to compromised online banking details, the installation of computer viruses and the obtaining of personal information.
Officials at the National Fraud Investigation Bureau are undertaking enquiries around a number of alleged companies who are exploiting people this way.
Officers at the Serious Organised Crime Unit say Microsoft and Internet Service Providers will never contact people by phone to say that their computer has been compromised and can be fixed for a fee.
Their advice is to never give out your bank details to anyone who cold calls and never let someone you don't know have control of your computer remotely.
It comes in the week that the latest Crime Survey for England and Wales has revealed there have been 5.1 million incidents of fraud in just one year and 2.5 million instances of cyber crime.