But first, yes. Even WPA2 is hackable FOR A PRICE. Read http://www.ghacks.net/2009/12/08/wpa-cracker-offers-online-cloud-cracking-service/

Since you can cause them to pay for said crack again and again by changing your wifi password, I advise folk to do this if they suspect such access.

Next there is a SCAM EMAIL about that. And there is the legit email. We never know which one. I suggest reading http://www.makeuseof.com/tag/what-to-do-when-you-get-a-copyright-infringement-notice/ but NOTICE THAT THE INDUSTRY IS EXPECTING US TO BECOME NETWORKING GURUS.

My tip? Turn off wifi when you can and why not the entire router?
Bob