Nexon Enterprise — legal notice

Address:

Dibrugarh, Assam, 786184

On 6th november a company named nexon enterprise sent me an agreement regarding captcha work of 10000 captcha which i have to submit in 10 days i was supposed to sign digitally and submit but i had only opened the mail they sent and the attachment containing the agreement is now disappeared and they asked me to sent one id proof and address prof which i have sent them and they provide me one login id and password for the work but i had no idea where to login so i called them back and they told me that the email contained everything but i didn't got anything from them and now they called me and ask me to pay 5200+3000 as utility charges and court fee for legal notice which they have sent me. I have no idea what to do so yesterday i called the person who sent me message on my number to provide me the agreement which i signed and the company details but he told me that he can't provide me companies private details and the message he sent me says they have sent me a legal notice of case under ipc act 420.
Please help me to resolve this issue as i have no idea what to do