Thanks gma45. That's kind of how I feel I should respond, and I've been doing that, but they don't seem to respect my boundaries. My supervisor keeps telling me next week will be better but it never is.

There ARE people who get what they want but they aren't all that reliable. I feel like maybe my reliability is not an asset in this setting and when I say I can't come in, I have to not come in. Hopefully they won't fire me. They seem to have a LOT of trouble keeping people.