Project not Releasing even after 6 years of dedicated service

Dear All, I have spent 6 years in a project and this year they gave me C band with reason of not going to office. I had been hospitalized in ICU 4 times last year and once this year for which I had proper RTO exceptions fully approved on the system by the HR. On top of that they are not ready to provide me onsite and next promotion when being asked for. Im always being appreciated by my customer regularly but TCS management does not value me.

Now when I got an Onsite opportunity long term and also my promotion is promised to be taken care of in another account, the current project is not releasing me. They are playing games by getting email confirmation from their local RMG and HR that I cannot be released for medical leave. I want to desperately available the other account opportunities.

Can some suggest what I should do here?