Organization not releasing my service letter

Hi, I have joined an organization on 11 Jan 2016 and had resigned from the same in late October and served two months notice period and last working day was 9 December. Here are few facts: 1) I had signed a bond of one year which stated that I had to pay an amount equal to three times my gross salary in case i resign from one year. 2) they did not give me a copy of the singed agreement on the first day.And during my notice period I asked for the same multiple times still they they did not provide the agreement that I signed or in the offer letter that my salary will be withholded.Other employees serving their notice period were paid their salary of every month. 3) They withholded my salary for the month of October and Novemeber on the pretext of recovery of the bond amount.What I can recall it was no where mentioned in the agreement. 4) I have already paid an amount of 94 thousand as per my withholded salary.They have dropped me a mail to pay and amount of 59000 more. 5) On the same mail I asked them to give me a copy of the service agreement but they havent done so.I have dropped at least 8-9 reminder mails but they are not responding at all. 6) Despite raising all the concerns to the HR that they are asking me to pay 1 lakh 40 thousand amount just for falling short of my service agreement.They didnt paid any attention to it. They process all the exit documents on 7 itself .So if I dont get it by this 7, I will get it next month. I have to furbish the same documents to my new organization. Please tell me what best can be done in my case.