Sds Solution — demanding money again and threatening for fir

I got call in june 2018 from someone asking for online form filling and ask to sign online agreement failing to fill form i have to pay 4900. When i submitted forms it showed many error in qc but i was sure it is deliberately done because in some forms i noticed it wasn't what i have filled.
After failed in qc their lawyer called and mailed asking money otherwise threatened for money which was 5600 higher then was in agreement after i paid they asked to pay extra 2100 for noc and file closing i paid that too. Later i realised i got cheated.
But i let it go.
Now today almost after 19 month another advocate ashok desai mailing me asking money otherwise threatening for fir. Mailing from [protected]@gmail.com and calling from [protected]
Please help me i can't not pay again to this trap.
Anyone know how to handle this please help.