Violation of the appointment policies

Dear Sir/Madam, I am working in a Pvt. Ltd. company that is basically an It educational center. I am working in this company from past 18 months. My total work exp. is around 9 years. I joined this company for a Chat process. It had been mentioned by the HR and the manager at the time of the interview that my job responsibility will include chatting with INTERNATIONAL clients only and bring business to the company. It was all good Till Apr 2017. But, now our Sr. manager has been asked to leave our process due to xyz reasons. So the HR head of the company is now been designated as our manager. From the day she is appointed, She is making her on laws and harassing the team. I ma one of them . Our appointment letter states Mon- Fri working but in brackets (timings can be changed by the company). We also signed a bond for two years for a sum of 2 lakhs. We have now been asked to calls for Domestic and International clients as well as chats from Domestic clients. Also we are working for 6 days now forcefully (that includes a Sat or Sund). She says that was can take a comp against it but, if someone asks for that, she becomes arrogant. I will be highly obliged if I can get an advise if we can take any legal action against these deeds ? We signed the bond on the conditions that we will take international chats and our night shift will be from 6:oo pm to 3:30 AM (from home), She now forced us to do a graveyard shift (12 Am to 8 AM) stating it as a companies requirement. So as they have changed their policies, does that bond still stands up or it is Void ? Also can they forcefully ask us to do additional tasks that were not in our job profile when we joined the company? I am not medically fit. I have high cervical problem and anxiety disorder. I told her that I will not be able to do the Graveyard shift as my health does not allow so and I am on medicines. But in vein. Few people have already resigned due to this cheating, mental pressure and harassment. is there any law that can help us, the Pvt.Ltd firm employees in this situation I am new to this platform and not sure if we get a response or not, but if legal advisors do help on this platform, I will be happy to provide any additional information and will be obliged Thanks