Can't Access My Call of Duty Mobile Account After Switching from iPhone to Android

I'm having a major issue with my Call of Duty Mobile account. I used to log in with my iPhone, but since I've switched to an Android device, I'm required to sign in using either my Activision or Facebook account. The problem is, I don't have access to either of these, and I can't seem to unlink them from my game account.
If possible, I'd like to remove both connections, but if that's not an option, I'd at least like to unlink the Facebook connection. Without this, I'm completely locked out of my account where I've invested so much time and money. I've searched through countless articles online, but I haven't found any solution to this problem.
Can you please help me regain access to my account? I'm really frustrated and don't want to lose all my progress and purchases.