***Validated Best Answer as of 03/2019***
Possibly because the ETF might be different depending on your specific agreement. Your particular fee should be explicitly defined in your contract, which you can find at the post that was linked above:
Visit my.xfinity.com from your web browser and select the My Account tab.
Sign in using your XFINITY username and password.
Click the Settings tab.
Click the Legal Agreements & Contract link under Account Details on the left-hand side of the screen.
Click the View link to see more details about your contract and/or legal agreements with Comcast.
In my contract, the ETF is defined in paragraph 5 of the Terms and Conditions:
... View more