Other thread by the querist is at:
https://www.lawyersclubindia.com/experts/Workplace-harrasment-and-bullying-late-working-hours-514876.asp#.VJ5byddAQ
8hrs/day...48hrs/week beyond which OT is applicable............there is a cap on OT hrs.
Employer should pay OT along with monthly wages and employee should claim OT in reasonable time.....
Look into ( name of the state) Shops and Commercial Establishments Act of the state and also ( name of the state) Shops and Commercial Establishments Rules framed under it and various forms that employer has to maintain to record the work hours/OT clocked on each day by employee.................
Standing Orders(certified/Model) might also be applicable
Download the evidence of assignments of tasks and hours clocked on each date and claim OT.
Employee's Unions/trade Unions, Labor Law Consultant/Service matters lawyer, Inspector appointed under ( name of the state) Shops and Commercial Establishments Act and Payment of Wages Act, O/o Labor Commissioner can be approached.................