Riot Games Changed My Valorant Account Email Without Permission

The email address on my Valorant account was changed without my knowledge. My Riot ID is bee#winx0. I noticed about three days ago that the email address on my account had been changed. I can still log into the game right now, but since the email address no longer belongs to me, I believe it's only a matter of time before my account is fully stolen.
I suspect that someone other than me has taken control of my account. I was logging in from my own Windows PC. I never made purchases directly through the game, but I did buy VP from a third-party site and used it to purchase skins in-game. When I tried to resolve this issue through Riot Games support, the system kept throwing errors, so I wasn't able to complete my support request — which is why I'm reaching out here instead.
Since the email address currently on my account isn't mine, I'm also unable to change the username or password, and I have no access to any of my security settings. I'm requesting that my account be secured, that the email address be changed back to one of my own choosing, and that full control of my account be returned to me.