All perfect praise be to Allah the Lord of the Worlds. May His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
You (Asker) must honor the terms of the contract and inform the people in charge about your situation since it is unlawful for you to keep silent about something while you know it is in breach of contract. Moreover, a Muslim must be keen on avoiding ill-gotten money and observing honesty when dealing with others. You must remember that Nawwas bin Sam'an (May Allah be pleased with him) reported: "I asked Messenger of Allah (PBUH) about virtue and sin, and he said: "Virtue is noble behaviour, and sin is that which creates doubt and you do not like people to know about it." [Muslim]. And Allah The Almighty Knows Best.