My Facebook Business Manager Administrator Role was REMOVED and moved to employe from an external unauthorized user. Restore my administrator role and remove the external user.

my facebook business manager has been hacked and I’ve been moved from the administrator role to employe role. So, inside my business manager so I have an external user that I haven’t authorised that is actually administrator of the business manager. I want someone able to restore the previous situation, removing him from the business manager and restoring me as administrator of the business manager.