Private college not issuing experience and reliving letter

Hello sir, I was working with private College as a lecturer, recently resigned from my position, but they denied to issue reliving letter and experience letter. Without relieving letter I will b unable to join another College. I raised this issue to labour commissioner through mail. He asked there is no provision in law for this issue , he only help in termination or salary issue. Or submit any proof of law/act for above mentioned issue. Request to all respected Advocates plz help me with law/Act for same , so I can submit printout to labour commissioner. Thanking you