PayPal IPN for disputes/chargebacks - php

Question

So I am working with the PayPal IPN for a payment gateway in my store project. Users can create stores and add a paypal gateway which is just storing their PayPal email.
How can I listen for chargebacks on that payment so I can then act upon that. Please note that I obviously do not have access to these paypal accounts, so I cannot setup a listener in their paypal.
When I create a payment I am building a query and then sending them to that URL, in that query is the notify_url, will that be used again if someone were to create a dispute on the payment. I tried to create a dispute however nothing seemed to happen to my database (What the notify url does).
Any help would be great.
Here is a the codeigniter library I am using:
[CODE]
class Paypal {
var $config = Array();
var $production_url = 'https://www.paypal.com/cgi-bin/webscr?';
var $sandbox_url = 'https://www.sandbox.paypal.com/cgi-bin/webscr?';
var $item = 1;
/**
* Constructor
*
* #param string
* #return void
*/
public function __construct($props = array())
{
$this->__initialize($props);
log_message('debug', "Paypal Class Initialized");
}
// --------------------------------------------------------------------
/**
* initialize Paypal preferences
*
* #access public
* #param array
* #return bool
*/
function __initialize($props = array())
{
$config["business"] = ''; //Your PayPal account
$config["cmd"] = '_cart'; //Do not modify
$config["production"] = FALSE;
#Custom variable here we send the billing code-->
$config["custom"] = '';
$config["invoice"] = '';
#API Configuration-->
$config["upload"] = '1'; //Do not modify
$config["currency_code"] = 'GBP';
$config["disp_tot"] = 'Y';
#Page Layout -->
$config["cpp_header_image"] = ''; //Image header url [750 pixels wide by 90 pixels high]
$config["cpp_cart_border_color"] = '000'; //The HTML hex code for your principal identifying color
$config["no_note"] = 1; //[0,1] 0 show, 1 hide
#Payment Page Information -->
$config["return"] = ''; //The URL to which PayPal redirects buyers’ browser after they complete their payments.
$config["cancel_return"] = ''; //Specify a URL on your website that displays a “Payment Canceled” page.
$config["notify_url"] = ''; //The URL to which PayPal posts information about the payment
$config["rm"] = '2'; //Leave this to get payment information
$config["lc"] = 'EN'; //Languaje [EN,ES]
#Shipping and Misc Information -->
$config["shipping"] = '';
$config["shipping2"] = '';
$config["handling"] = '';
$config["tax"] = '';
$config["discount_amount_cart"] = ''; //Discount amount [9.99]
$config["discount_rate_cart"] = ''; //Discount percentage [15]
#Customer Information -->
$config["first_name"] = '';
$config["last_name"] = '';
$config["address1"] = '';
$config["address2"] = '';
$config["city"] = '';
$config["state"] = '';
$config["zip"] = '';
$config["email"] = '';
$config["night_phone_a"] = '';
$config["night_phone_b"] = '';
$config["night_phone_c"] = '';
/*
* Convert array elements into class variables
*/
if (count($props) > 0)
{
foreach ($props as $key => $val)
{
$config[$key] = $val;
}
}
$this->config = $config;
}
// --------------------------------------------------------------------
/**
* Perform payment process
*
* #access public
* #param array
* #return void
*/
function pay(){
#Convert the array to url encode variables
$vars = http_build_query($this->config);
if($this->config['production'] == TRUE){
header('LOCATION:'.$this->production_url.$vars);
}else{
header('LOCATION:'.$this->sandbox_url.$vars);
}
}
// --------------------------------------------------------------------
/**
* Add a product to the list
*
* #access public
* #param array
* #return void
*/
function add($item_name = '',$item_amount = NULL,$item_qty = NULL,$item_number = NULL){
$this->config['item_name_'.$this->item] = $item_name;
$this->config['amount_'.$this->item] = $item_amount;
$this->config['quantity_'.$this->item] = $item_qty;
$this->config['item_number_'.$this->item] = $item_number;
$this->item++;
}
}
// END Paypal Class
/* End of file Paypal.php /
/ Location: ./application/libraries/Paypal.php */
[/CODE]