Cannot access last bill for the account closed last week

Last week, I went to a store to stop the Internet service and return my equipment. The guy there did not ask any questions and just told me that everything is done. Then I've got an SMS and email with a link to access my last bill, but the link actually does not work. When I click it, the Xfinity website asks me to log in, then immediately redirects to my previous account for an address that does not even exist any more. Clicking "Switch account" simply redirects to the billing page for the same previous account.

How can I access my last bill for the account that was closed just recently?

P.S. Apparently, Xfinity has completely abandoned the online web support, as there is only a stupid AI bot telling me to call a phone number. Calling that number and going through another stupid AI bot led me to a "40 minutes wait time" for a human representative. Completely unusable "service"...