Dear Ishwar Kumar,
In your post, you have not mentioned to whom you sent the reminders and how they were sent. If 90 days have passed since your last working day (LWD) and the Full and Final (FnF) settlement is still pending, you may send the application to the Managing Director (MD) of the company. Send the hard copy by Speed Post. Scan the hard copy along with the receipt of the Speed Post and send it by email. Make a file and preserve all the correspondence carefully. Hereafter, make all correspondence through hard copies only.
In the application, you may include your service details such as your employee number, date of joining, date of leaving, and your designation. Then, mention to whom you sent the reminders and what reply you received. Let us wait for the reply from the MD. If no reply is received, then send a reminder through hard copy after a fortnight. If still nothing happens, then we will see what to do further.
In your correspondence, please be polite. There should not be even a tinge of aggressiveness. By the way, have you received the Service-cum-Employment Certificate from the previous company? Has your Background Verification (BGV) been done? If the BGV is still pending, then please wait until the BGV is completed.
Thanks,
Dinesh Divekar