Comcast has inaccurate data usage monitoring, and poor escalation processes

[JTEmery]

My data usage "increased" by a 300gb a month starting in October 2020. I have unplugged my modem for several days and my data usage still goes up. Comcast has data usage ceilings that are put in place to generate revenue, and they generate false data to achieve this, knowingly or unknowingly (both are just as bad).
 
I am told (in error) comcast has no way of monitoring my actual usage because I'm using my own Cable Modem without their "software". I am not going to RENT your terrible combo router/modem. I am also very alarmed I was transferred by a comcast employee to a car insurance scam phone line en lieu of CSA.
 
Once my case was PAINFULLY escalated to CSA they asked for my modems MAC address to "investigate". 
 
Thank you Comcast. You have wonderfully lived up to your reputation again.
 
 

[NoNoBadPuppy]

Are you streaming video on a TV (Netflix, Disny+, Hulu, Amazon Video, etc)?  That counts against your data limit. The normal channels in your package do not, just the data consumed while streaming video.  Some home security systems consume data if you have the video feeds to a monitor in your home.  I understand that you have unplugged your router for extended periods; that would indicate that whatever is using data is connected to the modem (assuming you have seperate router/modem).