Fnf payment deducted and termination given without any notice

Dear Sir, I used to work in a company named ISDC( institute of skill developement corporation) from june 15 2017. They gave me offer letter at the time of joining and after that they gave me company asset and id card and business card. But they did not gave me appointment letter . on 10th of july i got june months 15 days salary but no salary slip of that even after numerous follow ups. Suddenly my father got ill and I needed to visit him on emergency visit on 10th of august. On 9th of august i received my appointment letter and there a clause was written that notice period for confirm employee is 3 month and if notice period is not served then i need to pay 3 month salary, details about this was never mentioned in my time of joining. And i took a leave informing one day prior i.e on 9th and they purposely rejected my leave . But due to the emergency situation, my flight ticket was already doone so i left a mail to consider my leave and than left. At that day they hold my 1st june - 30th june salary and they told my salary will be given after I return but they didnt gave, instead they gave me a discharge letter on 16th terming me absconding. Above all they didnt even let me do notice period, still than also they cut my june months salary which is unjustifiable and a clear case of fraud because i was probation employee so i had 1 month notice period. Now they told me that they will give my full and final cutting one month salary from 1st june to 10th aug whereas i took the leave on august. i was about to receive almost 37000 instead I am getting 9000. And I am a single earner of my family so it is a very big issue . Kindly suggest me what to do.