I'm having the same issue, it started at the end of November. For at least 2 years, I didn't use more than 10 gigs a day and then it jumped to 50 a day. I changed out my router and modem and changed my password but it continued. Cox technicians have been to my house twice, one installed a filter on my modem but again nothing helped. I only had 1 desktop computer hardwired to the modem and don't stream video or music. The tech said to unplug my computer ethernet cord when I'm not using it and that did stop the crazy usage but I know something is wrong and Cox can't figure it out. My husband got a new computer Saturday and is using wifi on it and our data usage somehow went down a little! I wish I could give you some advice but I'm still using almost 40 gigs a day and no one knows why.