How to change a job if the parent department declined your r

I am working as a Clerk in District Courts Sangrur since March, 2013. I want to apply for the post of UDC in PSPCL which is another public sector undertaking. I have asked for permission from my department and the same was declined. Then I write for personal hearing before the learned District & Sessions Judge as to why the permission was denied. He said that they have shortage of staff. But I want to apply for the job. Kindly suggest me what should I do.