These have been coming through a lot recently, people calling pretending to be from one of the big broadband providers.
First off, you haven't been infected with anything, Microsoft or any of the other big tech companies are not going to phone you up and tell you about an infection, because they can't tell, and certainly the people who provide your router can not either.
I spent half an hour with one caller the other day who took me through all of my system logs, they were for the general errors that happen on any system periodically, before trying to get me to install a Remote Desktop viewer, so that they could log onto to my computer and steal all of my information.