My full and final has not be done by the company

Hi Worthy Lawyers, I have left company on 23rd of April and they asked me to sign some uncontitutional document. On the last day i clearled that i will sue this document in the court and they released my releaving letter now my 45 days FnF is pending . its been 2. 5 month i did not get my salary of 55 days. 1) I send many emails but they never replied. 2) I send the legal notice and he did not reply to that instead he replied to me on another email that i did not work for past one year still they paid salary and now i asked client to pay me on another account and they are doing investigation. 3) No investigation is for the infinite time and i put the google review with that uncontitutional so called seperation agreement. On top of that many people old employe give bad reviews as well. Now i want to put defamation on company for lying that did did not work but fact is i was project manager so worked with various cross teams. i denied for signing this letter and all allegation has put. I have by accoutn staterment which clearly tell i never have any international payment received. On top of that company is saying this is the standard practice they follow to get this doc sign. I am lawful citizen and happy to fight for justice. Please advice how can i proceed as this can happen with any on. On top of that most upwork profile has fake photos .