That has happened to me 2-3 times. The first time I was sick. When the call came, he said my Windows has been sending out all kinds of signals of trouble but they could fix it. He told me to go sit in front of my computer and he'll tell me what to do. I told him I was sick and couldn't do it. He asked when I could do it. I said when I got better. He told me if I didn't do it right away, he couldn't be responsible for what would happen. When I got off the phone, I called Microsoft and told them what happened. They said there was nothing wrong with my computer and they don't make calls like that. I got another call like that a couple months later, and I told them "There's nothing wrong with my computer and I figured they were just telling me to sit in front of my computer to do something to give them access or get personal information. They got the wrong person if they were going to do that but I kept thinking of all the people who fall for it.
If you ever get an e-mail from some company (PayPal, ebay, etc., your bank) asking that you call them or they will halt use of your card, never call on the number they give you, or on the site they give you to click on. Instead, go to the particular site and use the "contact" link or call them.