NIIT — migration document

Address:

New Delhi, Delhi, 110018

I have completed my bsc it in 2011 from niit janakpuri and this institute tie-up was with kuvempu university and the tie-up just end recently.
As i completed my bsc-it and also got my degree but somehow dint get migration document from the university that time but now i required it for taking admission in higher education. But when i visit niit and asked for migration document, they denied to help me out and told me that we can't provide you any support now as tie-up already ended. But my main concern is where should i go for migration document as i never directly communicate to university ever.
Just confused and really frustrated the way the staff are talking (Niit) don't want to take any responsibility for earlier student who passed examination from same institute.