Sometimes the only thing to do is take a deep breath, count to ten and then get control of the situation for the day, however seems best. I do have the option of calling the office, but that's a last resort and, should it ever come to that, I'd be filling termination papers at once.
Honestly, parents tend to be more difficult to deal with then their children. The kids are much more likely to, eventually, accept that I'm in charge then their parents - who are, on adverage a foot taller and ten years older then I am.
I've found natural and appropriate concequences work well with maintaining disipline. For example, I had one little girl insist that she was too tired to help with our afternoon tidy up. So I gave her a choice - She could either help tidy the room, or she could go to the sleep room and lie down - but she was not to take any toys or books with her. I also told her that, if that was her choice, then next week she would have to take a nap with the other napping children instead of staying awake for quiet activities. She choose the sleep room and daily naps next week.
I suspect that she'll be less eager for a nap next week, but she'll be taking one for awhile. While I'm pretty sure she was actually just wanting to get out of tidy up time, following through on what I say is important. And if she really was tired at 2:45 pm, then she'd benefit from a nap after lunch.