What to do if the university is not mentioning the subject on degree

I have completed a PhD degree, and am about to submit my thesis to the college library. The university has said I cannot mention the subject of my research on the first page of my thesis. Till now all thesis have carried the subject/field of study. The rules were changed at the time of my final Viva. Also the degree I will be given will have only PhD written, with no mention of subject/field of study or the thesis title. I have already requested the academic committee but they have refused to revise the rules for the same. I am the first student to complete a PhD in my field of study at my University. I feel that this will impact my future research and career prospects. My thesis is in no way related to other research studies at my University, and I would prefer that it were not inferred to be so due to lack of thesis field / title on the degree certificate. Is there a legal way to make them mention my field of study on the degree?