If you can afford Advocate, simply issue a registered notice stating facts as to how much amount was paid, when, through and purpose. The chronological efforts made by a student for such refund and the assurances of Institution and finally their failure to refund which resulted in a deficiency of services and even fraud.
Specifically, inform them that student/consumer will be constrained to file a complaint before District Consumer Forum at......for recovery of fees with 18% interest, costs and compensation for harassment till now.
Avail free services of any voluntary agency dedicated to consumers locally if you want guidance. You need not pay single rupee towards court fees and the maximum expenses including postage and stationery may not be more than Rs.500/-. Being a student, learn to fight in your own way and seek guidance from voluntary agencies or from District Forum.