Something I've been using more lately that seems to work well is isolating them after class and, with the KT's cooperation and translation, asking them questions about their own behavior in class. They always like to act out and then act innocent. It's a typical pattern, and reminds me of...someone I know...when that person was their age. So I ask them questions like "How do you feel your behavior was overall in this class, evaluate it?" stuff like that, and the KT translates.
It goes totally against the grain of how they tend to discipline people, which is more in line with how we might scold a pet who poopoos on the floor, but so what? Broaden their horizons in the process!!
Instead of lecturing them about what they've done wrong, ask questions that guide them to acknowledging wrongdoing. Of course, if it's a larger group than this is more difficult to do, but then you might want to try isolating a few primary instigators with after-class discipline/coaching and send a stern message to the rest of them that way. They don't like it when you take their break time, anytime. It sucks for you too, but the pay off is classes will run more smoothly, after a little while, if you're consistent with it.
I don't even have to lose it with students. I have the kind of naturally commanding voice that even when I get into second or third gear, in a disciplinary tone, they think I'm on 9 or 11. Co's, too. They have no idea... I do have to be careful about that sometimes, but generally I receive compliments across the board from cos for my ability to manage the classes, much to the chagrin of students at times, I'm sure.