What should a person do if their manager oppresses them by denying them their rights and bonuses, refusing to respond to their complaints, and even punishing them for not being hypocritical, and deliberately humiliating and marginalizing them at work, especially when there is no authority to hold this manager accountable, and with their attempts to find another job having failed?

If your manager insults and oppresses, you have the right to report him to the authorities, if he can be deterred. Otherwise, complain to Allah, for the supplication of the oppressed is answered. "And whoever defends himself after being wronged – for them there is no way [of blame] against them." (Quran 42:41). If you endure patiently and forgive, you will receive a great reward, for indeed, that is of the matters [requiring] firm determination; "But whoever is patient and forgives – indeed, that is of the matters [requiring] firm determination." (Quran 42:43), and "So whoever pardons and makes reconciliation – his reward is [due] from Allah." (Quran 42:40).