ticket CS, that is basically your only recourse.
now, if you are a person who has like, millions of open chrome tabs at all times... check if you have an old recruiting page up (from before the guy signed), the recruiting home page, you can fix it there. you can also fix it yourself with something like the postman plug in or burpsuite proxy intercept, by submitting an AP change on a player, capturing the post, and changing the recruit id to the id of the already signed player... if that stuff happens to be in your wheelhouse.