Over last months many people have been reporting a rise on fake IT supports calls, those call claim to be coming from Microsoft support and try to make you think you have problems with your computer so they will ask for remote access and then charge for an expensive support fee (this is the best of the cases).
Sometimes they can tell you that it is a free support due to a problem generated from Microsoft, they will ask for some personal information in order to steal your credit card info and all the info they need to use it some days later.
Once they have permission they can let viruses and malware installed in order to monitor everything that you do and especially looking for credit card information, bank user names and passwords.
Please be aware of this scams calls, never let control of your computer to anyone you don’t know.