Site not really down.
Site:
I have been receiving the same "We'll be back shortly" for weeks, but called the support line and they had me try a different browser. I was using FireFox v46.0.1 but tried IE v11. It worked.
Once in, it's obvious that they've rolled out an updated site.
The support rep said she'd pass on the info about FireFox not working to their technical group.