Paul and Silas endured all this. They could have asserted their rights as Roman Citizenship when they were being accused of being Jewish agitators subverting Roman law and order. But instead they gave up their rights and freedoms and endured suffering. 

What happened to them was unfair but their response is shaped by their citizenship of heaven rather than that of Rome. Instead of being angry at their treatment and protesting they pray and rather than planning revenge or scheming to sue, they sing. In the darkness and pain, they turn to the Lord.