Always finish what you have to say even if others start trying to talk over you. If you stop it makes it look like what you have to say is not important. Check out this YouTube video titled: How to stop people from talking over you. https://youtu.be/ikAfrKf5A8I The YouTube channel Charisma on Command have a bunch of great videos on EQ.
I'd argue that much better way is to back off for a moment and try more diplomatic solution.