We are using Contact Form 7 on several websites. It had been working previously on this website, but had now stopped showing validation errors and does not refresh when the submit button is clicked. It does send the form, but since the user does not know this they continuously keep clicking the "submit" button and we get tons of submissions from them. Here's a link to one of the form pages.
We have the latest version of Contact Form 7 - 3.0.1