Hi there, @DarthQueenKit.
When you unlink an Xbox gamertag and link it to a new EA Account, you lose all progress on all EA games. That means all your Apex Legends characters would be reset. Along with any Ultimate Teams, Battlefield soldiers, Battlefront characters, etc. Due to how damaging it is to your account, we need to verify you own the account. If you're not providing enough accurate information to our account recovery team, they won't be able to verify ownership and give you access. The best I can recommend is that you try filling out that form again and make sure you add new information that could be more accurate than what you previously provided.