Mr. Dalmia has given valuable advice. Kindly follow it.
If in April you were serving notice period then for last 3 months employer is sitting on the payment of your wages. This is unfair and bad. It hints that employer is unwilling to pay. Any more wait shall be wastage of time. Employee has a right to demand interest and damages.
In a given situation employee can invoke the provisions of Industrial Employment Standing Orders Act, SE act applicable to the state, Payment of Wages Act, ID act as per explanation of employee under these enactments or approach civil court.
Ideally company should handover all dues and payables and documents to employee by last day in office or within next 2 days.
In your case you have notified the company of last day in office/ effective date of resignation one months in advance and it was sufficient time to obtain all kinds of clearances, NOC’s, KT, handover, exit formalities, exit interview etc. etc.
While you have fulfilled your part of contract by serving notice period and exit formalities employer and its Hr personnel should fulfilled their part of liability by settling the a/c in time.
HR has unfounded view that it has to hold on to the payables as it may have amounts to recover and adjust in FNF statement. An organized company would know by a click of the mouse payables by employee.
You may narrate all representations by phone (mention date, time, phone number, name of person called) in person, by email, letter etc, to your lawyer and let your lawyer by a notice under acknowledgment addressed to good offices of your appointing authority, MD, CEO, Chairman, Company Secretary, with a copy to Head-HR, reporting authority, and conclude that despite gentle reminders and representations payment of your dues (give detail) and documents (give detail e.g. Relieving letter, form 16, attested copy of PF withdrawal or transfer forms, FNF statement, work experience/service certificate, NOC/NDC, etc) has not been supplied and demand that payment of your dues by bank DD and documents should be supplied to you by redg. post so as to reach you in next 7 days, failing which appropriate forum may be approached.