For other users reading this, here is my standard reply to the many many threads on same topic:
That's a scam!
Do not allow access to your computer.
Just hang up on those scammers.
Microsoft doesn't call you if you didn't ask them to call you.
Do not trust unsolicited calls. Do not provide any personal information.
Please read:
Tech Support Scams – Help & Resource Page
**Tell Your Relatives: No, Microsoft Won’t Call You About Your Computer**
**The “Tech Support” Scammers Called HTG (So We Had Fun with Them)**
Cheers,
J