复杂的Symfony2表单生成器

I have an application where a game is played on a tablet device and if score is high enough it does an ajax post passing the score to a Symfony2 form where the user enters their name.

The issue I have is that the Symfony2 form thinks the form itself has already been submitted and so produces an error.

Does anyone know how I can fix this? or if there is a better way of doing this?

Any help much appreciated.