Tech support is available.
How to reach support (FAQ) - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=2421771&SiteID=2
You can also cancel your subscription and obtain a refund by contacting support. The automatic renewal was authorized by you when you originally subscribed to OneCare as a part of the subscription agreement.
Note that you will generally read about problems in a community forum. Without knowing what problems you've encountered, I can't comment on your experiences, but am sorry that you are not happy with OneCare.
-steve