Can't access any cox online bill services

When I log into the cox website and try to access bill pay (https://www.cox.com/ibill/home.cox), I just get a blank page with nothing on it. The http status code returned is 200.

Other pages that require authentication (https://www.cox.com/resaccount/my-profile.cox) state "Oops! We can't find that page." with small "500 Error: Internal Server Error" text at the bottom, and a 500 status code is returned.

I can't even access the chat support pages for similar reasons, so that's why I'm posting this message here.

This has been happening for at least 6 months. I thought it might go away over time, but it still persists.