My Konami E-Football Account Hacked During Trade

My game account was hacked during a trade. The reason for the hack was that I attempted to trade my account in the game. The person I was trading with assured me that I could trust him and mentioned he had security measures in place. He also had a large number of followers. He took my Gmail and password. Then, he changed the Gmail and password linked to my game account and took it over. When I messaged him on Instagram, I realized he had blocked me. Later, when my cousins messaged him, he responded to them in a rude and dismissive manner before blocking them as well. The game I play is E-Football, and the company is Konami.
Finding a resolution as soon as possible would be greatly appreciated. Thank you in advance.