Thanks Ray, I got it working as follows:
<?php
@session_start();
if(isset($_GET['sent']) && $_GET['sent'] == "true"){
// WA_ClearSession
$clearAll = FALSE;
$clearThese = explode(",","WASF_contact");
if($clearAll){
foreach ($_SESSION as $key => $value){
unset($_SESSION[$key]);
}
}
else{
foreach($clearThese as $value){
unset($_SESSION[$value]);
}
}
}
?>