Hello @kosmoss,
Thanks for writing in!
I checked the website and contact page in Chrome and Firefox, upon filling up the details and clicking on the submit button the form is getting submitted and I can see success message.
Having said that please note that WordPress does not support IE 9 or 10. It supports Internet Explorer >= 11. We follow the guidelines laid by the WordPress community. Even though our products run fairly fine on old browsers, unfortunately we can’t provide support for IE 9 or 10.
I suggest you to post the issue you are facing on Contact Form 7 community forum as it falls outside the scope of support we can offer:
https://wordpress.org/support/plugin/contact-form-7/
Thanks.