My employer is not processing my complete F&F amount

Actually, I worked with a company till Dec 2015. I worked as a manager. I was asked by the company to resign from my post as they were not able to afford my wages. So I resigned in Nov 2015 and served 2 months notice period as per the company policy. But by the end of Nov 2015, HR department emailed me saying that I need not come to office in Dec and they will pay my Dec and Nov 2015 salary through F&F. they paid half my Nov salary on request. Now, they are saying that they will only pay for the basic salary of Dec as I did not come to office in Dec and also they would pay other components including PF. I send them an email and stated that they had promised to give me Dec salary and I would not be able to accept only the basic salary. Thereafter, they are not even replying to emails and phone calls. I had planned to pay off my debts with this money. However, since its been more than 3 months I have not the money, I have not been able to pay off the debts, I am going through mental trauma due to this. What should I do?