Keydus Technology — asking for money with fake agreement

Address:

Thiruvananthapuram, Kerala, 695010

I got mail from online job for Captcha works that they sent login details through mail and was assigned to complete the job in 10days i.e to enter 10, 000 captchas and now they are asking for money to be deposited in their account and have sent some advocate letter saying its sent from their legal department and case will be proceeded soon if payment is not done.
Is it not fraud? should i pay them the amount in Keydus technology or will i have to face any legal cases?
please help me know more about this issue and how to handle this.
They are repeatedly texting me and threatening to give them money else they will file the case they are saying.
Can someone pls help me in this issue