F O Technologies — complaint against f o technologies (fake company)

I was going through google typing applying for part time job where i came across indiafilling and through that link i got FO technologies and i clicked on the link. After some time i got a call from them and they explained me the job that i have to type 900 pages within 9 days and i have to submit on 18.2.2019 before 12am and per page is Rs. 25 and also we have signed a promisory note. They have Whatsapp me to download one app and has asked me to log in. After completing the entire work today as i have submitted to them before time they said your QC is not accurate so you have to pay Rs. 8200 as penalty. If you fail to pay we are going to take legal actions against you. I got a call from one advocate dMr. Sharad Gupta) threatening and demanding to pay the money or else to go through legal notice. When i asked about the mistakes they are not ready to share anything instead demanding to pay Rs. 8200. I asked about their company details they are not ready to share the same. In the promisory note, they haven't mentioned any point stating if the QC is inaccurate you are liable to pay Rs. 8500. They have sent me a mail to sent the pay the money ASAP or else they will sent me legal notice. I tried to reach out to the helpline number all the numbers are not reachable and its getting connected to Gujarat and not Maharashtra. Even i tried to mail them in [protected]@gmail.com and also searched in Google i came to know that its a fake company and unlike me a lot many people are there who had fall to their prey.
I am attaching all the screenshots below