Delay and later denied Appraisal while termination.

Hi, I started working in a MNC (Tech company) on 24th November 2017. Due to their policies I got only one increment till 2019 and that too was not consulted with me. I reported this to HR but HR said that appraisal process is closed and should inform them next year if this happens again. In Feb 2020, I was released frrom project and spent 3 minths on bench and in May I was asked to resign as acc to company policy I had remain unassigned for 90days. To which I agreed, but I waited for May's salary as yearly appraisal is usually completed by May. But that didn't happen. I called HR, and he said company has decided to shift appraisal process to Q3 of 2020 and employees leaving before would not get any increment. Thus increment is pending as of April and since they are asking me to resign, they should pay me increased amount of Apr,May. Please help me if I have any legal option here to get my increment? FYI: currently I haven't resigned, I have 1 week left. And after that I'll have to initiate my release request and I'll get 3 months salary advance.