function updatecart() {
   var url = "https://secure.bellonline.co.uk/cartcontents.php";
   var script_id = null;
   var script = document.createElement('script');
   script.setAttribute('type', 'text/javascript');
   script.setAttribute('src', url);
   script.setAttribute('id', 'script_id');
   script_id = document.getElementById('script_id');
   if(script_id) {
      document.getElementsByTagName('head')[0].removeChild(script_id);
      }
   document.getElementsByTagName('head')[0].appendChild(script);
   }
function callback(data) {
   document.getElementById('cartboxtop').innerHTML = data;
   }
updatecart();