Sneha constructions — Asking for extra money in black for noc letter (Sahmati patra)

Address:	411023
Website:	housing.com/in/buy/projects/page/10469-sneha-homes-by-sneha-construction-in-warje

I have paid all the amount to the builder, and now I want my NOC(sahmati Patra) letter, But he is asking me to pay extra amount for it.
Please help me out to get my sahmati patra as soon as possible, because i am not ready to pay him extra money in black.