There have been a lot of questions and concerns from customer about what to do when they get a pop up on there screen, or in some cases receive a solicitation phone call.
The first thing to remember is that Microsoft will not call you, unless you've call them first.
Never call a phone number that randomly appears on your screen. If you've falling victim to these scams already, and have granted access to your computer to the representative on the phone, disconnect your machine from the internet and remove any programs that asked you to install, (Logmein rescue, GoToAssist, TeamViewer).
The next step is to reconnect your computer to the internet and update your anti-virus/anti-malware software and run a complete scan of your machine.
There may be things left on your machine even after this is done, if you are still concerned about someone getting access to your machine you should take it to a professional to have them look over the machine.