O C Technology — Data entry fraud

I was called by oc technology saying that they will give me part time job of captcha writing for 10 days with 90% accuracy.for this they will provide me 30000 deducting the registration amount of 6900 .they send me an agreement naming a contract with TOPS TECHNOLOGY kheda Gujarat. I started working and within two days I realised that the license agreement stamp is fake as it didn't contain signs of both parties. now I realised it is a big fraud and if I didn't do the work they may ask for money or take any legal actions. I don't want to continue doing. what should I do