As a referee, I have used a push or tug on the shoulder to de-escalate a situation. I started as an ice hockey referee and linesman, so learned some useful techniques to do it safely (linesmen are expected to break up fights and pull apart combatants). When I started refereeing rugby, I was able to transfer those skills. »
Except as referees, we are taught that a series of infringements in "the red zone" can be grounds for carding, regardless of repetition of a given offence or the same player infringing multiple times. If you feel there is a pattern of cynically breaking the laws in order to stop a team from scoring, you can certainly card someone...typically it's the next bloke that infringes after you have a stern chat with the captain.