/regarding unnecessary termination

Hi there, I have joined a company 3 months ago, during first month salary salary was credited on 21st but as per documents it's 15th when asked from employer he says you will get your salary after 20 then i don't say anything but now without giving and prior notice or written warning employer has terminated 3 employess by saying that he is not satisfied with the performance and when asked to pay for noy=tice period he refused and finally given post dated cheque which is dated as 15th july 2019. which is valid next month and when me and other employee asked why you have given post dated cheque he says it's your punishment and further on threatens that i will hold the amount if you will ask any other question do what ever you want i have no fear niether of police nor for any labour court go where you want to go. Company is pvt ltd company and cheque is named with companies current account and dated 15th july '2019. and also when we asked for experience letter he only says i will send termination letter on your email account not experience. Please suggest what can be done i am living in east delhi and company is situated in barakhamba*(new delhi)