Avi Enterprises — fraud agreement and then blackmail

There is a company name avi enterptises fraud captcha entry. The member of that fraud group message message for the online job.. That time i agreed. They are use fraudulently my name as a signature in their fake agreement and send me a mail in which shows that if i cann't do that work within a time limit then they take a legal action against me and also then i have to pay the registration amount of 6900. I was not aware about agreement. Then i started working but after filling so many captcha it shows 0 again.. Then i came to know that it is a fake company who fraudulently take a money from people in the name of legal action.. Please help mee sirrr and cancel that fake agreement... Now i am also in a problem i know after some time they call me or send me a legal notice for the money 6900. Sirr please help me before they blackmailed mee.