I am not aware of any legitimate, legally operating "gigolo agencies" in Kolkata.
India's laws (Immoral Traffic Prevention Act, 1956; various state police acts) criminalize organized prostitution and solicitation. Entities advertising such services often operate illegally, may be scams (advance-fee fraud, blackmail), or fronts for trafficking.
Strong advice: Do not engage. Risks include legal consequences, financial fraud, physical danger, and exploitation. If seeking companionship or counseling, use reputable, licensed platforms or professional services.