Oc Technology — Demanding money

I applied for work from home in quikr. I got call from OC technology and she told that about the work that. You will be given with 10, 000 captchas, you need to do work with 90% accuracy. Instead that you need to pay 6900.i accepted by giving my aadhar as proof. As I stared work second itself it get didn't start. Now they demanding me to pay a sum of 6, 900 to pay and also sent advocate notice.
Requesting help