Experience Letter Alongwith Two Months Compensation

In my last organization, I have been asked to resign and they have issued me only relieving letter on my last working day but they did not give any compensation to me. After few days when I sent an request email to ask about my two months compensation and full and final settlement, they have called me in the office to discuss the same. They stated that if you need the two months compensation then you have to sign on termination letter also you will not be eligible for experience letter. And at the time of resignation they did not say me that you are termination case. They simply ask me to resign, so I did. Again they have taken back my original copy of relieving letter from me and now they are saying that you have only two choice on that basis they will issue me my further letters. I was working as an HR there and in the past for the same kind of cases I have given experience letter alongwith 2 months compensation to such employees. But now they are saying you have only two option either accept the relieving letter with no compensation or accept termination letter with 2 months compensation. I was the person who took care of the employees in night shift. I used to work in office for 15-16 hours daily. I used to work on every weekends to meet the business requirements. Most of the time I worked for 4-5 shift. I am not saying that I did not commit error, sometime yes. But I need the answer if any person who take care all the activities who works for 15-16 hours daily cannt make the mistakes. Also I want to bring one more thing into your notice as my appraisal was effective from Dec'14, but they have delayed the process and they did not give the appraisal. Finally they announced that they are going to roll out appraisal on 07th Sep 15. But before 8 days they asked me to resign (i.e. 28th Jul 2015). As per legal, I should be eligible for appraisal as it was delayed from their end. Please suggest if I can go legal against them and will I be eligible for my experience, relieving and 2 months compensation.