@ scrupul0us, perhaps you are confusing his $SESSION['POST'] variable with $POST[' var_name_here']? 😉
Yes for sure, these variables must be sanitized and handled with care.
@NZ Kiwi.. as weedpacket mentions.. there is nothing in your code that tells us where you get the value for $_SESSION['POST'].. so if we don't know where you get this value, how do we know if your switch / case statement is working or not? We need to know what gets stored into that session variable first. And it doesn't hurt to include a default in your switch statement..
switch ($_SESSION['post']) {
case 'NZ':
$PostValue = "5.00";
echo $PostValue;
break;
case 'AU':
$PostValue = "13.00";
echo $PostValue;
break;
default: echo 'Error: No POST value found...';
break;
}