There is no "edit" function to update my billing address on the website.
Anyway I can use my current service address as my new billing address?
Please see https://www.xfinity.com/support/articles/updating-your-mailing-address. You can't change this yourself, you need to have a Comcast rep make the change for you. If an Employee doesn't reply to your message here, contact a phone or chat rep (1-800-Comcast, or see https://www.xfinity.com/support/contact-us).