My current employer not relieve me

Respected sir, I am working for 20 month and I have resigned through E-mail and submitted Hardcopy of mail to Technical manager before 30 days. As my notice period is 90days I discussed with Technical HOD to relieve me after 30 days with notice Pay of 2 months. After completing those 30 days when I asked for Relieve at that time HR-Manager Forcing me to serve 90 Days and not ready to accept notice pay and says like that it is written in your appointment letter to serve 90 days so you have to serve I cannot accept notice pay. Now I am in trouble that I have committed new employer to join after 30 days after discussed with Technical manager. But now Both manager are not giving answer. Unfortunately for this I don't have any proof except the mail which is I mailed but there are no reply from the manager side. So should I have to left current employer and join new? Can current employer take any legal action? ( I have submitted all stuff provided by employer) Or suggest me other options