Stuck in a Notice Period Dilemma: How to Handle Policy Changes After Resignation?

I'm working in a pharma company. I have a service bond for 2 years that I agreed to when I joined. They provided me with an appointment letter at the time of joining, stating that my notice period after resignation is 1 month. Now, after completing 2 years, I resigned 2 months ago. However, my employer is not releasing me in one month as stated in the appointment letter. They are now saying that the company policy has changed and I have to work for three months compulsorily. The issue is that my joining date at a new company is approaching. What should I do?

Thank you.

Hi Damu,

Was there a notice informing the change circulated to all the employees?

No, sir, there is no information about that. When I asked my HR to provide the document for changing the notice period, they denied it and told me to go and ask my HOD.