National Institute Of Open Schooling — Name correction in my 12th certificate

Address:

H no-8-3-231/173/C, Sri Krishna Nagar, yousufguda Hyderabad

My name is bodala sai teja i completed my 12th from nios but there is a mistake in my surname i need to correct it in my certificate but nios is not allowing me from 2019 i a have been trying to correct my name but they are saying they will only make correction three years from admission but now my name is different on my 12th certificate and ssc certificate that makes me un qualified for any government jobs and private jobs so please help me