I have a probleme with submit form (booking) it re-submit on page reload
this is code of conditions to post :
if ( 'POST' == $_SERVER['REQUEST_METHOD'] && ! empty( $_POST['action'] )
 && $_POST['action'] == "new_post" ){ 
       if(!empty($_POST['start']) || !empty($_POST['end'])){
        // submit and send email}  
}
after submit it show thank message and details of booking ( else it shows errors and the form) but if user reload page it re-submit a post again in database!
can someone give me an idea , i tried to unset $_POST['end'] and $_POST['end'] but nothing works 
Thank you for your support
 
     
    