Forcing to sign 3 month bond after completion 2 years of Bond

Hello Dear Sir/Mam I am working in Private company as Software developer. I have signed 2 years of bond at the time of joining (6month Training Period+18 month working Period) from April,14 2014. But now they are forcing to signed 3 month extra bond after completion of 2 years. They forcefully said, you have to signed up 3 month bond otherwise We will not give appraisal of January which have they given in written by mail on Aug 14 with 20 to 40 % of current Salary. For Appraisal I have signed 3 month bond but in Appointment letter written that you have to serve 2 years of bond if you break the bond you have to pay remaining time salary. They also keep my original document and 18,000 Rs (6 month x 3000Rs =18000 Rs) deducted at the time of 6 month training period. We have also asked by mail and orally to deduct PF and Form 16 but they are not providing yet. They said company is not legal to provide these facilities. They self made new policies again and again prior notice period was one month but now notice period is 2 month now 3 month bond. Is it possible to take action on Company? Is it possible to break bond in March before 15 days completion of bond by giving remaining time Salary? Is 3 month again bond is legal by the company ? Company made new policy is it apply for prior(old) employees? How can i legally left the company because they are not trustworthy and how can i get my original document by the company? Thanks