Problem in getting relieved from college

Hi My name is Balaji. I am working as assistant professor in ECE department in a reputed engineering college in Tamil nadu. My problem is, Our college was getting fund under TEQIP II programe. I initiated a purchase of an equipment for our department under that funding. According to the rules I must organize a workshop to train the faculty in the department on how to use the equipment. I organized a two days workshop in that connection. I followed all the rules and regulations while organizing that workshop. I got permission from the HoD of the department and also displayed a circular a week before the training program, got the willingness of the department faculty members for attending the program. About ten faculty members accepted to attend the program but only two attended the program other than me. This happened two months back. Now I submitted my resignation on 12.06.14 and asked for relieving on 18.06.14. According to the rule mentioned in the appointment order i must give three months notice period or failing which i must pay 3 months salary. I agreed to pay three months salary. HoD signed my resignation letter.But now she is not signing my no dues form and she also says I have not conducted the training program properly. She says that I conducted the training program for my personal benefit. She is asking me to conduct another training program and says only then she will relieve me. Everything that i have done (Purchasing the equipment, conducting the training program) was for the benefit of the department not for my personal gain. What should I do now? Kindly advice.