F&F Dues Clearance - Ex Employer

Respected Sir / Ma'am, Sub: My previous employer not doing Transparent F&F Dues. I have joined my Previous organization(XYX) in May, 2014 and I have put up my papers in Jan'2020. As per my HR norms, I have to serve 2 months notice period which I served. 1. We have a Variable Pay which 10 % from my CTC( Part of my salary Structure), They don't want to pay. 2. Duration with that Organization: 5.9 years 3. Last Working Day 11th Mar, 2020 4. My company FY starts from Jan to Dec and I have put down my paper in the next FY in the month of Jan. My query: After giving my resignation my reporting boss accepted and asked me to serve the notice period(2 months). Later my company CEO scheduled a one on one meeting with me and tried to understand my concerns and asked me to withdraw. They have promised me a salary hike and designation. They have issued an appraisal letter in which they have raised pay and promoted me to the next level. Meanwhile, they have hired the same level person in place of me to which I was unhappy and continue to leave the organization. When I asked for F&F, They are denying to release my Previous Year Variable Pay( Jan'2019 - Dec'2019. They have considered my previous year's salary structure and calculated my EL, Gratuity, and whatever the pay hike has been done that, they would like to deduct in my F&F. How can I get my Variable Pay and How can I ask them to consider my EL's and Grautity on current salary structure.