It is indeed a very difficult situation. If you report the matter to the authorities, the company will simply deny they have the passport as they are not authorized to keep it. Such companies do not give a receipt when they take away the passport of their emplyees. They may not return the passport at all creating further difficulties. Added to the problem is that once the visa expires, a penalty for overstaying may come into force. Take the assistance of your embassy. Possibly, they may be able to guide you better.