You have initiated many threads and have been repleid also.
The service conditions inserted in appointment letter are governed by various enactments.
Depending upon if the employee/designation/nature of duties is covered by such enactments then even if soem illegal T&C is inserted in appointment letter it shall be void.
You may better consult an able labor Law Consultant/service matters lawyer with copies of all docs on recored and also seek support of Employee's/trade Unions and thereafter once you have understood the finer aspects of your case you may approach:
Inspector appointed under Shops & Estbs Act ; where you were located, O/o labor Commissioner at location where you were posted/or company has an office/or where Redg office or Corporate office of the company is located/ or the jurisdictional courts as inserted in appointment letter.....
Or direct labor Court (State/Central) as applicable in your case