Mp Services — fraud and harassment

A person contacted me through whatsapp that they are providing online form filling job and i have to provide a residential proof to register. I submitted them and they provide me a login id and password and a 15 day window to submit the work. After 15 days when i submitted the work with accurate accuracy, they refused to acknowledge my work and said you have violated the legal aggrement and now have to pay 4900 + 3000 rupees. And now they are harassing me on daily basis through calls and messgaes and emails. I have searched on internet and found that other people have also became victim of this fraud. They had also made people fool with other company names such as dg services or uni services.
Their lawyer is continuously harassaing me to pay the amount although my work was up to the mark and threatening me to send legal notice at my home.
The lawyer number is - [tina]
Kindly help!