How can I address salary and promotion issues with management?

I am facing several issues with a government officer regarding my salary and promotion. Firstly, my overtime salary has been reduced multiple times without any written or verbal communication; the officer has been overwriting and changing the time period I submitted in the prescribed format. Secondly, he issued me a show cause notice for a misunderstanding, and when I attempted to submit my response, he refused to accept it. Additionally, a promotion order was issued by a higher authority, with some officers approving it on the same date. However, my officer approved my promotion three days later, resulting in a loss of seniority and jeopardizing my chances for future promotions. I approached the grievance redressal committee, but the senior authority has not taken any action. I would appreciate your guidance on how to proceed. Thank you.