I had booked a flat in a new construction project at Noida ext. I am applicant and my elder brother is co applicant. Now i want to change the name of co applicant as my wife . My brother is ready to give me NOC. The project is new and till now i had paid 30% payment , but no agreement has been signed. Builder is asking for 200/ sqft extra for the name change of co applicant.

Is this demand valid? From where i can get builder policy guide? Where to complain?