Full and final settlement not done

Hi, It has been 4 months (July end) that i am relieved from my X employer. I resigned in June first week. Full and final settlement is not done due to following reasons. 1) I was absent after April so i am being asked to return salaries of April and May. I did not receive June month salary as I resigned in first week. My last assignmnet was in S. korea 12X7 work. It was on a ship where it was 28 days on and off. So i was spending that 1 month after i returned in April. Meanwhile S.Korea project went on hold and i was told to visit USA for another project for which i was interviewed by USA client. For that i went office for couple days. I left rented house for S. Korea project which lasted for around 1 year and 2 months. So i had to return home town. My company is in Mumbai. USA project also got cancelled due to some reason. I did not want to travel further so i resigned from home. which got accepted and i went office to return laptop and all belongings. I got relieved smoothly without any grievance. But after 3 months when i inquired about full and final settlement i was shocked. They asked me to return salaries. I am to receive medical insurance claim worth 200$, 250$ for my last trip, All holidays which i never took and other benefits. I am not receiving experience letter which is why my next employment is in dark. They have got me signed on a paper while relieving that i will not join any client company for 2 years. I am turned down due to this once. Further i have filed for PR for Canada which asks for experience letter. Is there any legal way i can fight this one off?