Unprofessional Experience with Izeon Innovative Pvt Ltd - Unpaid Work & No Appointment Letter - Network Engineer Izeon Innovative Employee Review

I worked for 1 month as a Network Engineer in Izeon Innovative Pvt Ltd. They told me in the interview that I had to work 1 month unpaid and from the next month they'd give me full-time work with a salary of 15k. But at the end of the month, they told me to work for extra 20 days unpaid and said they'd give me full-time after that. And they also didn't give me the appointment letter despite my repeated requests.