Koodo charged me for 1.2 GIG of data to transfer a file through Windows Explorer from my Galaxy 3 phone to my PC through a USB cable. They told me I should have disabled "Mobile Data" first. Does that make sense?
That would be really weird especially if your file was on hard disk of your computer and you connected your phone as USB storage. May be same or another file was downloaded directly via phone from online source without realizing?