You may submit a representation in writing under acknowledgment, addressed to good offices of your appointing authority, MD, Prop, with a copy to Head-HR(if any) and narrate the details. You may enclose details of payables by company to you, and detail of payables by you to company (notice pay), and ask the company to verify the details and supply you acceptance of resignation, work experience/service certificate, FNF statement, payment of your dues by bank DD, form 16, PF number/accumulation reports/attested copy of withdrawal or transfer forms as per your choice, by redg/speed post, so as to reach you within next 7 days. You may mention that postage prepaid (as purchased from PO) self addressed envelope for sending the redg post/speed post to you is enclosed.If as per correct FNF statement you have to pay the dues to company you may do so and obtain your documents from company.
If the good offices also do not grant relief you can issue a legal notice, and approach o/o Labor Commissioner, Chief Inspector under SE act, Wages Inspector or civil court as deemed fit.
You are HR executive so you would know how to proceed.