If your company is not giving the relieving letter and your the documents you can file suit for declaration in Civil Court in order to get the same
Also, a suit for recovery of the pending salaries can be filed in civil court .
Alternatively, insolvency petition can be filed in NCLT in order to recover your salary is along with interest and compensation.
You should also consider giving a written complaint to the assistant Labour Commissioner intimating of the illegal acts of the company against you and the other employees.