I just called Discover (888-DISCOVER) to speak to a supervisor about something, and was told there's no supervisor available. When I asked when/why, I was told that the regular supervisor is on vacation for the week. The CS rep confirmed that there's only one office that handles Discover Biz accounts and that office only has one evening supervisor...
I wonder how their shifts work, I'm thinking I'll try back after midnight.
At least their CS is all American IIRC.