Experience Certificate

I was working for a private university in the capacity of Asstt. Prof. since last 1.2 years on a consolidated salary. At the time of joining in offering letter, the terms and conditions said: 'services are liable to be dispensed with from either side without assigning any reason by giving 3 months notice in writing or payment of 3 months salary in lieu thereof. however, in case notice to leave the service given expires before completion of a semester, you will have to serve the university untill completion of the semester or to deposit salary for the residual period of the semester' to which i signed. However, in practice, company never paid 3 months salary to whom it fires anytime during or on completion of a semester. However, relives the staff at that time who choose to resign at that time. In my case, company not issued any letter of experience with the company when demanded while in service. as this is normally provided by most companies like my previous employer also did same, when was demanded. Further, i applied for Study leave for six months during semester end and before beginning of the next even semester. That however was accepted after great hesitation in Oral without issuing anything in written. salary of that month was also not released. Hence, 30 days before beginning of next semester it was clear that i will not be taking any subject in next semester and hence no breach of contract happens of imparting studies of the students. after,one month during that leave i got far better job, in better company, work culture, double salary in another state. to which, on getting offer letter, i sent resignation letter to my company, that was accepted, NOC cleared and all ID was taken. However, i was not issued Experience letter, on terms that i have to submit 3 months salary. It clearly seems unethical to me. What the Legal experts opine about suing? Pleasse revert