Your issue is like many of the employees that you are not properly informed.
1. Download the copy of resignation submitted by you and LWD issued by system. Write a letter by Redg. post or atleast an email from personal email id that you have submitted notice of resignation dated...................in system (preferably attach the copy if you can) and LWD issued to you is dated...............(and you will serve the full notice period issued by company by its system ( if you want or if you can).
2. Record proof (audio/visual/witnessed/minuted) of being asked to work OT, on weekends/holidays/off days. Include in your letter that on dated..................Mr/Ms.............stated that you will have to work on weekends/holidays/off days ( if you want or if you can).
3. Let them state in writing that ou will be relieved on 31-03-2016 or relieve you on anyday in writing.
4. Download all rules/policies mentioned in appointment letter, employee handbook etc
5. Has any blame been levelled on you in writing?
6. Download proof of delivering in time and upto satisfaction, completion of all assignments etc
7. Reply to all emails denying allegatins. Download email asking to work extar and OT, off days etc.......
8. Let them state your LWD upto 15th April or whtaever, in writing and download a copy or minute it in writing, under proper acknowledgment.
9. Download proof of complimenting you or minute it. Mention about certificate of appreciation. build record that during notice period you were not casual and did not cause any loss.
10. Download proof of shouting and denial of relieving letter or threat of adverse comments in it or minute it.
11. Submit leave application, intimation of leave in writing under proper acknowledgment, and narrate that you have informed the manager on dated....................by phone/SMS /email etc and it was approved verbally etc or manage to get approval even if by SMS etc.
What is your designation and nature of duties?
What is the notice period inserted in appointment letter?
Is there an office at Pune?
Are you a member of employee's/IT-ITeS employee's unions/trade unions.
Would your next employer accept you without relieving letter/with adverse comments in BGV?
Have you informed them in writing that your notice period/LWD issued by system is ................and relieving letter may not be issued to you? Manage to ensure that next employer accomodates you and does not terminate.
The proofs/evidence alone can rescue if a dispute precipitates.
If you are apprehending a dispute then consult an able Labor Law Consultant in advance ASAP.