Crossway Technology — data entry fraud

I want to complaint against croosway technology... I have recieved a call on 20 july from a company called sc technology.. They said that they will provide captcha work to me... They made a contaract with me in which they mention that i have to fill 12000 captcha in 12 days otherwise i have to pay 6000 rupees nd made contarct with me... I have not signed that contract.. After i started the work... After 3-4 days.. They submit report for that work.. When i check that report then i found that they cheated with me.. As in that report.. Those captcha are not the same as i filled in the website... I mailed them then they tell me that their concern will call me.. After 12 days completion.. Today on 5 august they mail me and said to pay me 6000 rupess.. I denied then they said that they will go legally against me.. Now they are not even talking to me.. And not picking my call... What should i do now.. Help me