Hi,
thanks for the link.
I took a look at your website and did some small tests.
I think, you will have received 2 form submission from me.
First of all, you wrote that you have published the forms with modules, which is actually true, but the modules are not published in a "common" way directly on the page. Instead you have these nice symbols on your website which displays a popup with the form (and other content). There is a lot of additional thirdparty code involved in that process, which does not take care of the requirements of Visforms.
Visforms, even the modul, is not designed for such a use in the first place and it cannot work properly.
I think, as long as any inputs which the user makes, including the captcha, are correct, this actually works. I have send you a screenshot of the page which I saw, after the form was submitted successfully, with private mail. I think, your thanksgiving text ist displayed there.
But if a user makes an incorrect input, especially an incorrect captcha, Visforms tries to display the form again, including an error message about the incorrect input. But, due to the way the form is published on your website, Visforms cannot redirect properly to the "form" page. It properly redirects to the page where the form modules are attached (in your case the faq page) but it cannot find the form there, due to the way they are published. And because the error message would be displayed inside the form, it looks to you as if just nothing happens.
Another problem is, that with your contruction, the captcha refresh button cannot work on the forms, either.
Regards,
Aicha