What utmost LEGAL ACTION can be taken by school authority if teacher leaves without any information but who served only 2 mos?

So the school name is Green Point Academy,Kulti, which is in proximity of Asansol in West Bengal. and i am from Durgapur, approximately 65km. I used to travel from a whole different city to another for this job changing three transports in only one part. Mentioning this because this was what drained me mentally and physically. Not everyday though, there has been different complexities around. 1st, the Principal of that school was the one to ask me for doing this job in the first place as their School Counsellor since there never has been any counsellor before. 2nd, When i told him regarding the difference, he said to work there as a part time basis, but that will be only within the authorities and me. But in the appointment letter, they will showcase me as a full time Counsellor. I still agreed on the same and went for only Wednesdays and Fridays. 3rd, They promised to provide me a salary of rs.15000 INR for these 8 days (only within the authorities and me) but instead put up the same salary in contract with me. (Principal saying after signing the contract, he will increase the amount to 24,000 - 25,000 next month) 4th. Since DAY 01, until the last day of leaving, I HAD ABSOLUTELY NOT BEEN DOING ANY WORK AS A COUNSELLOR BUT FELT LIKE MORE OF A PERSONAL ASSISTANT TO PRINCIPAL'S DESK. The principal was my reporting manager and he kept on giving me tasks which were not at all relevant. After a whole month, he started to try on sticking around me by wanting to drop me home. (driving 60km, since we both were from Durgapur and he came by car, i went by bus). He kept on nagging about his family issues, wanted to take me out sometime else, etc. etc. I started keeping boundaries and swept away on seeing him or fled away from school directly as the shift went over. When i went to straight face tell him about not liking the job and leaving it, he said not a single word. And pushed me to chairman's office for asking to leave. The chairman insulted and shouted on me. Then looked through the contract! It was mentioned in the contract to pay off 45000 as per my salary, three month's salary in advance to the school. But i only worked for 2 months and i left literally saying that i shall pay back once i join somewhere and get the salary from them. Also, not to put up any resignation letter officially! So i didn't. Now suddenly, today after 1.5 months, i am receiving a letter from the school signed by the principal stating that i have to give them 45,000 INR and else legal action shall be taken against me. But WHY! EVEN mentioned that i couldn't be contacted in any way whereas none even tried to contact me. This is where i am stuck. Can i get some suggestions as to what to be done in. Such a way so that I don't get indulged in court cases and also put 15000 and can get through this sooner? I never thought 2months of helping out people will put me here one day.