Why do I have to delete all xfinity cookies every time I want to log into billing?

I already know this doesn't belong under the chosen topic, and that's because Xfinity refuses to list the actual web site anywhere in the systems as a topic for discussion. So here is the nearest to it.

Subject says it all. I'm using Firefox on Linux Mint. Every SINGLE time I want to load the billing page, the web site goes into a death roll of continuously reloading a series of pages none of which ever load. I can't get into billing without deleting ALL Xfinity cookies every single time. Can someone at Xfinity PLEASE report this issue to the IT team? This cannot be fixed on our end.