Incorrect Data Usage

I've seen several similar posts on here as well as reddit but it seems like a resolution is never reached.

In December I got the email that I was nearing my data cap, I didn't think too much of it at the time, extra days home, holidays, all that stuff. However after looking into it further it seemed that my usage had been growing quite a bit for several months. There is no reason for this as nothing has changed as far as additional devices, people, etc. I use an eero system at home so decided to compare the usage numbers:

October: Xfinity - 707GB, eero - 308.6GB

November: Xfinity - 880GB, eero - 421.2GB

December: Xfinity - 1.09TB, eero - 433GB

January (so far): Xfinity - 198GB, eero - 61.1GB

I reached out to Xfinity today to bring this up and of course the first thing they did was to try to sell me a rented modem (I use my own), the second they did was try to upsell me on unlimited data, and finally when I said that wasn't the issue, they asked me to reset my WiFi password. After explaining that I am able to get detailed usage on devices on my network they said they would open a ticket for the next level team.

All said, I am dubious that I will get a response or a successful resolution here. Has anyone else who has had simialr problems had any luck?