How to approach central labour commission

I am a part of a registered trade union of a PSU and our pormotion has been illegally stopped for last 2 years. We have raised  numerous demand letters but to no effect. Now we want to move to CLC for concillation.

Please inform whether we can send a simple letter to CLC briefing about the fact or we have to go through the procedure available under Industrial Dispute act (Central ) for starting of a concilation.

Please help.