Unable to access old secondary email account

I have a secondary email account that is no longer accessible.  We moved and no longer have Xfinity as our internet provider.  However, I cannot change to a different email address, because 3rd parties want to send a verification email to the comcast.net address, which I cannot access.  Trying to reset the password just takes you to a page that says get on your home internet.  Well, therein lies the problem since I have no home Xfinity internet to get on to.  There needs to be some mechanism to allow managing/resetting passwords for situations like this.  Please advise.