Frontech — threatening for money

I got a call from them on 30th april regarding online form filling work and Ms Anjali naik was the representative and her mail id is [protected]@gmail.com .so i started working from 31st may .I was supposed to submit 1350 forms from 1500 forms which is 90% accuracy ..Which i submitted on 9th june
And after 3 days they generated the QC report is failed and next day an advocate called and mailed me to pay the money of 4500 which is the registration fee else they will file a legal case against me .
So because of this i paid 4500 as stated in the agreement and after that also they are asking me to pay the 2 times of the registration fee to continue or if you want to terminate you have to pay 3 times of the registration amount .
I am not willing to pay the amount anymore so I want to file a complaint against them as they are calling and messaging me again and again...so kindly help me to resolve this issue