Xfinity, why was I billed after cancelling for service you won't provide?

@XfinityRoberto​

My account number is in the private message I just sent to Xfinity Support.

Your bills are paid in advance for services that have not been provided yet. Since I cancelled before my payment date of 17 December, I shouldn't be charged anything for any future December+January service which you will not provide.

Thank you so much for this information. For security of the account. May I have you delete the post with your account number. Let's take a look at this for you in private.

Please send us a direct chat message with your full name and complete service address to “Xfinity Support”. To do so, click on the chat icon located at the top right of this forums page.
Here's the detailed steps to direct message us: 
 • Click "Sign In" if necessary
 • Click the "Direct Message” icon (upper right corner of this page)
 • Click the "New message" (pencil and paper) icon
 • Type "Xfinity Support" in the to line and select "Xfinity Support" from the drop-down list
 • Type your message in the text area near the bottom of the window
 • Press Enter to send your message

Let me know if you have any questions.