Job related

Dear Sir/Mam I was working for an organization where they hiered me in a provision period and doesnot provided me with any sort of training related to sales. I was handling marketing and sales and my salary was 17k in hand. After completion of 1 month and 10 days in that organization they sent one mail stated that I am not fulfilling their sales criteria and in that email it was clearly stated that if I fail to perform they will take some corrective measures in 30 days but they terminated me before 30 days stating that I am not fit for this job and they also mentioned that they will provide me the salary for the previous month for which they were going to inform me, but unfortunately they didnt informed me so I called them but again they gave some lame excuses. Today I mailed them in which I have mentioned all instances that occured in between us and I got a reply stating that my mail was an audacious attempt and they are not willing to speak or want to have mails from a non performer like me. The mail hurted me please help me how to take my salary out from them and I wanted to book a case against them for harassing me and putting bad obligations