You have rightly observed that :
"Billing was completed for this job and issue is between 2 comapnies."
You may clarify whether the following statement posted by is made in writing by the company or verbally and by whom and also is it in response to your written representation:
"Wen I asked for my settlement comapny management told that either I can make a cash or DD payment of the outstanding due from the customer or have to wait till they settle the outstanding."
Your resignation was accepted in writing?
Was there any communication to you to fetch any payment for the company?
Do you have NOC/NDC, acknowlesdgment of handover of charge?
The FnF wages/payouts should be paid on LWD, since you had submitted notice of resignation and during notice period employer is obliged to process everything related to smooth exit.
The FnF wages could have been paid say within 3 days from LWD or max. by usual pay day.
Has the company supplied acknowledgment of notice of resignation/final resignation, acceptance of notice/final resignation, FnF statement showing all payables to you e.g. earned wages/perks/emoulments/bonus/incentives/reimbursments/leave encashment/gratuity etc and all payables by you e.g. notice pay/recovery if any (passed after opportunity of natural justice and by a speaking order) and final amounts payable by either employer/employee, Form16 as per correct FnF statement, PF a/c slips of all years, salary slips of all months including notice period,ESIC card,service certificate,relieving letter etc..................
You may demand everything from good offices of appointing authority,MD,Chairman by letter thru Redg. Post so as to be supplied to you by Redg. Post only say within next 7 days.
In this letter you may amke a gentle mention that your representations in office on dated....................to Mr/Ms...................have not fetched you any releif and supply of pending docs and dues.................................and avoid making mention of any amount/document that has not been claimed from you in writing.
The forum where you can agitate shall depend upon coverage of your designation and nature of duties.