Procedure to change the category of tc post issue

Taken TC after 8th standard in Bangalore. Now post 6 months we have got the right category certificate where as the caste is the same. Now we need to change the category, we have the certificate from Nadakhacheri.com for caste/category. The new school is saying unless the old school changes the certificate, they will not change. And old school is saying new school can change. What am I support to do ? what should be done? please advise.