TATA CONSULTANCY SERVICES LTD - Unfair FFS arrears

Tcs told me to be on medical leave as advised by the medical counselor from and have a written document saying the same. And they have credited me five month salary in full and claiming when it was their mistake of management and hr. I was under the impression that tcs does good for it's employees hence used the salary to pay my rent and family expenses and now I put down resignation with Tcs as Night shift was hurting me and got a job in a bank. They are not releasing my relieving letter and experience letter which crucial in my new job and will be fired in absence of it. I have all documents supporting my cause and well versed for claiming the deserved amount for irreparable damages done by them.