Full and final settlement

Hi, Due to covid pandemic, company was closed from March 23rd,I stayed in bglre for two months then I came to native on May. Then,only staffs has resumed working from june onwards..but no Salary was offered.at that point of time,I couldn't come to office as there was no transportation. I ask for work from home option they didn't allow it..and I opted to give resign and settled in my native. I have given resignation on aug.they have accepted the same. I got my settlement paper through mail they added only gratuity and 1 year bonus only.so I have not given confirmation to further process. The issue is 1) company has not paid the bonus from 2016 onwards,4 year bonus is unpaid(They are telling can give only 1 year bonus) 2)they mentioned 31st March as last date of working in FNF settlement 3)I was there as a company employee till aug..but they are not ready to pay any salary from April to aug20.. This company has cheated may staffs like they don't do fnf,some deduction in fnf,no bonus,salary delay for more than 2 months,salary not paid from April20 to aug 20 ,still paying half salary to staffs also tds payment delay,pf payment delay,gst payment delay and they do some adjustments to cheat the government. Kindly suggest how to go ahead