Company not releasing from service and not giving documents

Hello Sir,Madam, This is Hemant here. My younger brother working as Software Engineer in Bhandup, Mumbai location. He wants to leave the current organisation and for same he had sent the resignation letter in October 2016. However the company told him that they do not have the notice period so he has to complete the project then company will release him. The employer had stopped his salary so my brother didn't went for a day and sent mail for salary and docs. In reply to this employer sent the mail saying they will send the legal notice to my brother and they threaten him using CA and one other partner. But then on 25 Nov 2016 they discussed and agreed that the project will be close by next month (Dec 2016) and post that he will get release. But the project has many dependencies on client side and technical front. So In last one month not much progress has happened. Whenever my brother ask for project to move the employer says we will talk to client. But nothing happened. My brother is going through stress due to this and want to get release. Can any one for you guide us on this. Thanks, Hemant.