Changing EA Game Account for Inquisition

This is a bit complicated. I've tried contacting EA customer support directly for help 3 times. Not only has it not been helpful, I have been given straight up misinformation multiple times. I'm not sure what else to do.

I started playing Dragon Age on a shared XBOX 360. Whoever had played prior to me put in a fake email to play an EA game, so the EA account they created is inaccessible and there is no way to find out the password. I have my own EA/Origin account that I wanted to transfer my game files for DA:O and DA2 on to, but I don't think that will be possible. Instead, I used Dragon Age Keep to make a close enough world state. I am trying to change the EA game account that Inquisition is attached to. There is no place to log in or out and there is no place to change the EA account associated with the XBOX gamer tag. My only goal at this point is to at least play Inquisition on my own Origins account. Is there anything I can do? Even just to disconnect the fake account from the gamer tag?

I'm sorry if this question is a repeat - I've been trying to work on this issue for multiple days now and it's been very confusing.