Hello,
The best way to avoid any usage from being done without your knowing about it during the night, is to turn off your computer when you're not using it. Our usage calculator does not allow us to know the content or source of items downloaded through your modem. Actually, it would be illegal for Videotron to invade your privacy in such a manner.
If you own a wireless router, please make sure that your wireless connection is protected by installing an access key. This will secure your wireless network and will prevent other internet users to use your connection fraudulently.
Thank you for your understanding,
JoséeC.