Also, if you pull the plug on someone, I would assume she was firing her.
I'm more familiar with pulling the plug on a project (discontinuing it) than a person. Either way, it would not mean that she's gotten a stern warnings -- she'd be on her way out the door.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.
Thanks to your tips, we have decided to change the content of some units altogether. The students took the most active part in discussing the issue as well. We all, I mean my colleagues and myself, plus nearly thirty third-year students majoring in international economics, are grateful to all of you for your help.