All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
Among the firm established rules in the Sharia is what Allah says (what means): {…and no bearer of burdens will bear the burden of another.} [Quran 6:164]
Therefore, it is not permissible at all for the wronged person to take the right of others and oppress them as a way of getting his right from the person who wronged him.
If the purpose of that trick is to stop implementing the services for that man's clients to pressure him to pay what he owes you, given that those clients will be harmed by the delay of their services, then this is not permissible, because this represents doing injustice to the clients and harming them unjustly.
Also, among the firm established rules in Islamic law is that: Harm is not removed by another harm.
Az-Zuhayli said: “The harm is to be removed in Islam unless removing it necessitates doing a similar harm to others; then, in this case, the harm is not to be removed with a similar harm nor a greater harm or even a lesser harm. So, the harm of a particular person is not removed by harming another person, because all people are dependents of Allah and He made them all equally deserving of respect.” [Al-Qawaa'id al-Fiqhiyyah wa Tatbeeqaatuha fi al-Mathaahib al-Arba’ah]
Allah knows best.