On the page:
/includes/contact/send_email.php on line 4 you have:
$Email->Redirect = "".$_SERVER['PHP_SELF'] ."?sent=1&#success";
That should be:
$Email->Redirect = "".$_SERVER['REQUEST_URI'] ."?sent=1&#success";
I updated the file:
I made it so that it won't append a url parameter if the link has a hash "#" in it. That should fix the failed redirect issue. You will want to back that file up so you don't accidentally replace it later since it will be re-generated when you update or add server validations.