Quikr — sir i applied a fake job in in myc company now they are harassing me

Sir/madam, i had applied for online captcha entry job and i didn't know that this company is fraud and cheats/ blackmails people. Before registering they didn't give any information about their terms and conditions after registering i got to know that i have to pay amount to them. And after they provide the app to work with i immediately search for the app and i got to know that it is a fraud company and cheated many people. So i just call the executive who give me all the information about this and i said her to cancel my registration i am not going to do this job as i know they are fraud and the executive said me ok she will cancel the registration. Now, today i got a call to blackmail me that you have to pay the charges for registration and i am a student and not able to pay such amount. So, please sir/madam help me out and revert back