Fraud coaching institute

I was teaching in a coaching institute from July 2016 uptill March 2017. The coaching institute has its headquarters in Guwahati and it has a branch in association with a junior college in Jorhat. I was a faculty of the coaching institute in the Jorhat branch. One of my postgraduate teacher had introduced me to the director of the coaching centre. I had to teach class 11 batch of 30 students and droppers batch of 3 students. The director had promised to pay Rs1500/class basis. Duration of each class being 2 hours without break and 1 class a week for each batch. Bt the agreement was done verbally and not in pen and paper. Further they didn't give me any appointment letter. Initially they paid salary for july-november for class 11 batch. But they didn't pay me any money for the droppers batch from August-December. And promised to pay the complete amount at the end of the session. They had stopped paying salary from December altogether giving some or the other excuses. But they kept on calling me for the classes. If asked about the salary they would say we will pay u shortly. On multiple requests they didn't respond to me. So I left the centre and am asking them to pay my salary that amounts to 48000 for 32 classes. On enquiry it came to my notice that the Coaching centre has been continuously withdrawing money from the college. Further there was no registered record of my taking the classes. Only witness are the students and the management of the junior college. Moreover they have published my profile in the mentor section of the coaching institute. And also have manipulated my teaching experience without my consent. I have requested them to pay my salary but in vain. So I have warned them to sue their coaching centre if they further delays my payment. Now my payment of 32 total classes i.e. 20 classes of droppers batch and 12 classes of class 11 batch is pending. So I need some advice on how to withdraw my money from them.