Legal procedure to retrieving bonus on being relived in notice period

I joined company X in Bangalore on 1st August 2016 and received a joining bonus of certain amount. The terms of joining bonus states that I will have to return it if i "voluntarily exit" with in one year. I resigned from the company on July 3rd 2017 and offered to serve a one month notice period according to company's policy. That would have mean I would have left X on 3rd August 2017 and hence completed my one year. But the company is not not letting me serve the notice period and asking me to leave earlier. They are ready to pay remaining 20 days salary but they are asking to return the joining bonus. As this is not a voluntary exit but a forced termination, am I liable to pay the joining bonus amount back ? Please help, Thanks!