It really depends on the situation. Was it at a party where dungeon rules or your limits were not respected? If addressing the Dom involved would not work then I would suggest approaching the dungeon monitor. Most venues are very strict in ensuring that rules and limits are followed.
If you are referring to outside of a controlled play space again it would depend on the situation. Is it your dynamic or someone else’s dynamic? Some more context behind this might help us give you some more specific ways to approach the situation.