Just a quick note, confirming how hopeless this new Comcast “feature” is:
Comparing with last weeks post, apparently my data usage recently is ZERO! Apparently it’s possible to use 139GB in a month, 48GB in two weeks, but 0GB in a single week … amazing!
M&I / GBMINI 
I don’t have confidence that they reliably measure data. At least that’s from my experience with mobile carriers.
In my previous job we developed a job dispatcher type of application that communicated with mobile workers. Of course our customers wanted to choose the data plan for each worker that would be cheapest. We were never able to reconcile the amount of data we thought our application was sending with the amount on the carrier’s billing.
After many discussions with the carrier, we determined that every data transfer was being rounded up to the next 1K, and routing headers were added to every data packet that counted towards data usage. But in the end they couldn’t give us a definitive answer of how they arrived at the billing number! It says x Megabytes on the billing but the engineers we talked to couldn’t figure out how it was measured and calculated!
Richard