Termination of employment on the grounds of underperformance

I started working with this medium sized organization in August of 2016. As per the hiring documents it said 6 months of probation. I was hired as a sales and business development manager, and kept bringing them in leads. I kept reporting to the VP Sales and everytime I asked how I was performing he just said you have nothing to worry about you are doing great. I was made to work for almost 11 hours daily 5 days a week. Have never been late to office been on top of my job at all times. Suddenly on December 20, 2016 at 9:56 PM I get an email from the VP sales saying my employment has been terminated with immediate effect due to underperformance. He was not even in Hyderabad at that time for more than a month. So I asked his interim leads about this and they called him from their phone. I was not allowed to even speak to him from my own number. During my conversation with him. He said this was a decision he made and didn't even have answers for what I asked him. Is there any way I can actually fight this out. Moreover there have been multiple things that have transpired over those few months, like making me stay back at work for extra hours and not allowing me to take the cab back until he could leave, asking me not to speak to certain members of the team and make a formal complaint against them to the HR, trying to extract information out of me about the rest of the team at work, revising the incentive plan and cancelling my incentive money after the sale has been made, I'm not sure what to do now. Is there a way I can get help on this legally.