We were sent a bill for an account that is closed.

Hello user_aes4lr. I totally understand the frustration with receiving an unexpected bill. We can certainly check to make sure the account was disconnected as intended and see if that is actually a bill that's owed. Sometimes they send one out for the upcoming month before the disconnect fully processes. Please send us a direct message with your full name and the service address to get started. 

To send a "Direct Message" to Xfinity Support: 
Click "Sign In" if necessary 
Click the "Direct Messaging" icon or  https://forums.xfinity.com/direct-messaging 
Click the "New message" (pencil and paper) icon 
The "To:" line prompts you to "Type the name of a person". Instead, type "Xfinity Support" there 
- As you are typing a drop-down list appears. Select "Xfinity Support" from that list 
- An "Xfinity Support" graphic replaces the "To:" line 
Type your message in the text area near the bottom of the window 
Press Enter to send it.