How to edit user package

[mitchelp]

I would like to update the package of a user!

When a user have pack1 with tis settings:
150MB space
4GB Traffic
enz..

Would i like to update his package to pack2 with tis settings:
300MB space
8GB Traffic
enz..

How can i do that??

I have try this:

<?php
			$sock = new HTTPSocket;
			$sock->connect('summerhost.nl',2222);
			$sock->set_login('name','pass');
			
			$sock->query('/CMD_MODIFY_USER',
			array(
				'action' => 'modify',
				'username' => $username,
				'package' => $_GET['pack'],
				'notify' => 'yes'
			));
                   $result = $sock->fetch_body();
                   echo $result;    
?>

What dit i do wrong??