Query related to Notice Period and Resignation Policy

I worked in a University for 8 years and I left 4 years back. As per appointment Letter, I had to serve a notice of 3 months or pay a salary of 3 months if I wanted to get relieved immediately. After some years of my joining they changed resignation policy as per which you can get your 3 months security which was already with them if you resign in Feb and serve Feb-Apr. If you resign in Mar then you will bet 2 months security and if you resign in Apr you will get one month's security. And if you resign in May or after that you won't get any security and you can not even serve any notice even if you want to. (In short you have to resign in between Jan-Apr) for Semester 1. Same is the case for 2nd semester (you could only resign between Sep-Dec). I applied for an NOC to join another University in Mar, 2019 which they denied to give (had they given I would have got 3 month's security). Next opportunity I got in July and I left but I had to forgo 3 month's security as per that policy. Can I send a legal notice that by not allowing me NOC that they had blocked my right to get another job. How should I go about it?