Forgot my ID

Why cant you just use your username? I havent actually played this game in 2-3 years, but when I tried logging on using a different iPhone because mine was stolen, I didnt know my ID. Seriously every other online game or website doesnt have you remember a stupid ID number, you log in with your email or username. I spent hours and tons of money on this game, and now I want to play again. Unfortunately I cant because after 3 years Ateam still hasnt fixed this problem.

BurningPages about Dark Summoner, v1.07.01