Not sure what to say that hasn't already been said. Personally I think you are:

1.) Overreacting a little here.

Threatening to delete your character just because they don't give it to you right now? I can fully agree with you that choosing the wrong gender can make you want to avoid playing a character. I was about to delete my alt and restart over because I wasn't happy with his name. However that was due to some server error issues back at launch that made my changes fail to save server-side. Fortunately they gave me a second chance to rename so it's resolved. But threatening to quit the game and delete your character unless they meet your demands right now comes off as a little childish. Sorry but it is.

2.) Not telling the full truth.

Something feels off about your story. Obviously you KNEW you used your Fantasia, the only way (Unless SE lied on this.) to change your appearance/gender with the vial is to unequip all armor and then log out of the character. Not saying you might have unknowingly hit the recreate on your character but even then something should have alerted you something was off. Using a Fantasia only gives you access to change specific things, had you been creating a new character it would have prompted you to choose a name and profession. It would have even shown a different character, not the character you had before the change. In fact I'm pretty certain it displays the race/gender select screen first. In order to have changed your gender using the Fantasia you'd have to choose the option from the list first.

I feel you used your Fantasia, decided to goof around with different appearances. You found one that looked good and saved it as a template. Unfortunately you without realizing, hit the confirm button at the end and it permanently saved your change. I don't know how much else is accurate about your story but I'm certain you likely came here looking for sympathy and to rage, changing the story to favor your side.

In any rate, whether or not this is true going to the General Discussion board and posting these demands isn't going to get you anywhere except ridiculed as it has. Instead, I suggest directly contacting SE via other means or posting something in the help forums here in the correct section. General Discussion isn't the place for it. Wish you luck in your endeavors.