If you deal with people that display challenging behaviours remain calm.

Most times people get frustrated when they feel ignored, undermined or struggle to use their voice.

This approach can help de-escalating a conflict:

 Listen to them quietly

 Speak with a low tone and a warm voice

 Keep reasonable physical distance

 Reassure them 

 Avoid contradicting them

 Accept their reality

 Ask them what would be a good resolution for them

 Aim to arrive to a mutually convenient outcome