I am not listed as the Primary Account holder even though it is my account.

Nope.  Can’t do it there. The below line means I should already be the Primary account holder, so please fix it on your end.

”The account owner is automatically the Primary user.”

The primary user on the account should be the account holder, however if someone else activated the service or provided a different name / email address they would be listed as the primary user on the account and the users invited after that would be managed by the primary on the account. 

Since you are not showing yourself listed as the primary, I have a feeling that the account was activated with another persons details. You can try to find that ID by searching your account details. 
But I can also try to work and figure out how the account / primary was set up to guide you through making the corrections. Can you please send us a direct message with your name and service address? 

Here are 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

Done (extra characters to fill the quota)