Unfair delays in approvals

​I have been working under my current supervisor for three years and have completed all the necessary research work for my thesis. However, my guide is forcefully withholding my publication approvals so that I have to stay back and manage the lab administration work for free. When I submitted a formal application to the HOD to change my guide, the application was rejected without any valid reason, stating it is an internal matter. It has created a very toxic environment for my career progression.