IIFL — Regarding the relieving letter

I am writing here due to because of my relieving letter is not issued by employer (IIFL).I already served my Notice period as well but after that also they are not responding me for the same. As i already word with the Territory manager and Hr as well both are incorporated with as well. After that also hr is not entertaining as well now i am hopeless with this type of approach and many more are suffering from the same