How to get the passport and original certificate from recruiting agent who is not fulfilling the commitments?

Question

I was selected by a saudi company three months back? I surrendered my passport and original certificate to a local agent for processing visa two months back? The agent neither process the visa nor giving back the passport? The employer does not take interest to resolve the situation. The agent just giving excuses every week and informing me that the passport is with saudi embassey? how to deal this situation? Can any one through light for help?