Employer claiming 2 onths notice pay and denying relieving letter

Hi, My notice period when I resigned was 3 months. However, I had asked for an early relieving of 1 month after resignation date. My employer agreed to reduce notice period by 1 month only and issued a letter to me that my contractual end date and last working day would be 2 months after my resignation date. However, during my conversation with management, my director had also given me threats of dismissal. I was very much concerned and since I did not have much responsibilities at work, I approached the MD for early reliving. He agreed to cut my notice period to 1 month after resignation date. In accordance with this, HR issued another letter to me stating my last day of working and last day of employment both to be 1 month after resignation date. I served till this date, completed all exit formalities and left. Now, the employer has sent me FNF in which they are asking me to pay 2 months notice pay , have withheld my final salary and not giving releiving letter after repeated reminders