Company refusing to pay me full salary after resignation.

Company refusing to pay me full salary after resignation, deducting salary for non-working days and holidays. Am I legally entitled to this salary? I worked as a consultant at a CSR consultancy based in Ahmedabad for 6 months. I was asked to serve a notice period of 2 months, after working there for 5 months out of which 3 months was probation period. The working conditions were horrible and their way of conducting business was unethical, they were extremely rude to employees and I didn't want to work there anymore. I resigned by the end of the 5 month. From the day I put in my notice they started harassing me, like several other companies do. They did not acknowledge my resignation, stated questioning my work ethics, ignored my calls. I continuously asked them for a relieving date since I was applying for other jobs. I requested them to reduce notice period to one month but they never replied to my emails or calls. I asked them for a relieving date so I can negotiate with my new employer but they did not reply to my mails. I was not given any new work or projects but they refused to relieve me earlier. Since they wanted me to serve 2 months notice period, they refused to pay me for the first month. I have responsibilities at home so I had to beg and plead them to at least pay me for the first month. They finally paid me after a lot of following up and pleading. They still did not give me a relieving date, Finally I had to choose between giving up my new job or leaving mid-notice period. I informed them of my dilemma and told then I have no option but to quit. They threatened me with legal action, but I had already informed them I will handover everything and I have no issues in doing the same. Finally I gave all documents and they gave me a relieving letter and I got out of there! They told me they will send my full and final settlement in the next salary cycle. Now they sent me my full and final settlement calculations. They have deducted pay for all non working days and holidays, and non reporting days (days when I sent my daily work report late). When I asked them the justification for this, they said the contract conditions mention that pay will be deducted on non working days and holidays during notice period. These are my questions and I need help in understanding the legal aspects of it: I know they are targeting me, because another colleague who resigned has got their full dues. Although the contract mentions it, they do not deduct pay for all employees, only me. Is it legal to deduct salary for non working days especially when they ask to service notice period for 2 months. They have more than 80 employees but there is no grievance redressal committee or any neutral party I can go to for dispute resolution. I also have worked overtime ( on saturday and sunday) for 7-8 days while I was on site, but I am not being compensated for this. When I asked them the reason on mail, they again ignored the question. Can i claim discrimination/ harassment in this case to legally receive all my dues. They have harassed a lot of their employees, including asking people to leave in 3 days after probation which is against their contract conditions. Their entire organization is a sham, I am really frustrated and want to take legal action. What are my options? Does it even make sense to send them a legal notice? Thank you for reading this wall of text! TLDR; Company has deducted more than half of my due salary quoting contract condition that says "salary will be deducted for non working days and holidays during notice period". But they are doing this to harass me as other colleagues have received full payment.