Well, I'm back in, all around, like it always was. When I got unbanned, their system let me into the forum, but my account was still closed. The reason I could still access the forum on my Chromebook but not my PC was that the browser tab stayed open, and once I logged out of the forum/Ccom, it wouldn't let me sign on again. After reading everything I could online, and trying everything that was suggested - flushing DNS, turning off antivirus, disabling all extensions, opening an incognito browser, etc - and wasting tons of time doing all that to no avail, I called Ccom again this morning.
A wonderfully helpful person named Amy tried getting into my account, and even she was unable to access it. She vowed to look into it and 10 minutes later called me back to say that when I was unbanned from the forum, nobody realized my account had to be unfrozen too. I'm happy. I'd be happier if the person I spoke with yesterday had discovered the same thing and saved me all the grief, but whatever.