After I moved, I'm unsuccessfully trying to unlink the old account that Xfinity says was deleted from my new one.

To unlink the old account, I went through the steps given to me on chat:  Go to Account and ID; --> Xfinity ID & Security; --> Manage Linked Accounts.  At that point I get an error message saying "We are having some trouble connecting to My Account"; and then it logs me out.  Can't get past the Manage Linked Accounts step.  Also, my old account is listed as the default.