If you receive a phone call from someone telling you they are from Microsoft and that your computer is infected , hang up , it is a scam.
They will want to install software on your computer that is designed to gain remote access and once they have installed this software , they will inform you that they have found even more infections and even show you some ” bogus examples”.
They will then say that for $249 they will install antivirus software which will protect your computer in future and that will fix all these ” issues”
What they have done is infect your computer and got your credit card details .
If you have done this my STRONG advice is cancel that credit card and get that infection removed from your computer which in extreme cases will mean a format and reinstall.
For an analogy , I described this as letting someone you don’t know , come into your house and go through all your most intimate objects.
By the way Microsoft , Apple , Telstra will never ring you for this , never.