Login catch-22

I recently changed ISP and now have new email address. I can no longer access my OLD ISP and email at old email address

 My old email address is my Norton Acct Username.  When I try to update my Norton acct profile, the new username and password goes to my OLD email address....I can't update my profile until I update my username/password, but can't update my username/password until I update my profile.  Catch-22.  navigating Norton website and don't find a helpdesk telephone #.