data transfer??
 

If I see data transfer on my bill occuring every 1-3 minutes for hours at a time, during the night even, wouldn't that require someone to be using the phone - ie instant messaging? I think my partner is staying up and IM'ing someone...

Could be that or you left an app open and it is hitting the Internet for data. When you are finished using an app, especially one which uses data, hit "close" rather than just exiting out.