Email password reset, Iphone email broken -(plus 400 error on Xfinity reset page)

Lots of weird issues with Xfinity password today. 

1. 7am I get an auto email: "Your password has been reset" -- I did not go to my email or reset my password.

2. Later, I check email online. Xfinity forces a password reset. I create unique password. I do get email online.... BUT -

3. I cannot receive or send from this account on iphone 13. I enter the new password ten times. Try every step found on forums:

• Reset phone twice. try again,
• Shut off WIFI. Try again.
• Delete the email account. I cannot recreate email account with either old or new password.
• Request Reset password again online: The new password does not work.
• I try to reset again online, and now get error 400 Request Header Or Cookie Too Large
• Endless irrelevant AI Assistant loops - and on the Xfinity support phone line. All suggesting I RESET MY PASSWORD.
• I manage to reset it a THIRD time with a totally unique password. 
• I finally CREATE NEW EMAIL ACCOUNT: outgoing SMTP error: User name or password is incorrect.
• I paste in the new password FIVE TIMES. Same error: "User name or password is incorrect."

The account is setup but I can't get or send email. 

I can't get a human to help unless I drive to a frigging XFINITY store?

I've now lost all of my old emails on my phone. Including a lengthy email in my Outbox when this began.

You forced this reset. Your system is BROKEN.

I used to recommend Xfinity. NEVER.