Hi @terrydactyl86 , thanks for reaching out here on the forums. I'm sorry to hear you've not been able to link your Xbox account to your Ubisoft account, due to it having been linked to another account previously.
Our support teams are in the best position to help with this, as they are able to perform processes to verify ownerships of accounts to get them recovered - we can't do that from here on the forum, for security reasons. As such, if our support teams have been unable to recover an account, that's as much as we'll be able to do at this time. As you'll know, there are a great many laws and regulations around data security, so we cannot share information or make changes to any information without a means of verifying that the information belongs to the person we are speaking to.
My apologies for the frustration over this. Please let me know if you've any further thoughts or questions.