$url = 'http://dev.chargeover.com/api/v3';
//$url = 'https://YOUR-INSTANCE-NAME.chargeover.com/api/v3';
$authmode = ChargeOverAPI::AUTHMODE_HTTP_BASIC;
$username = '******';
$password = '******';
$API = new ChargeOverAPI($url, $authmode, $username, $password);
// The invoice we want to update
$invoice_id = 10009;
// Build up the object
$Invoice = new ChargeOverAPI_Object_Invoice();
$Invoice->setDate('2015-06-08');
$LineItem = new ChargeOverAPI_Object_LineItem();
$LineItem->setItemId(3);
$LineItem->setLineRate(29.95);
$LineItem->setLineQuantity(3);
$LineItem->setDescrip('Add this new line item to the invoice.');
$Invoice->addLineItems($LineItem);
// To keep the existing line item, you have to pass the line_item_id
$LineItem = new ChargeOverAPI_Object_LineItem();
$LineItem->setLineItemId(2575);
$Invoice->addLineItems($LineItem);
$resp = $API->modify($invoice_id, $Invoice);
/*
print("\n\n\n\n");
print($API->lastRequest());
print("\n\n\n\n");
print($API->lastResponse());
print("\n\n\n\n");
*/
if (!$API->isError($resp)) {
    $invoice_id = $resp->response->id;
require '../ChargeOverAPI.php';
//This url should be specific to your ChargeOver instance
$url = 'http://dev.chargeover.com/api/v3';
//$url = 'https://YOUR-INSTANCE-NAME.chargeover.com/api/v3';
$authmode = ChargeOverAPI::AUTHMODE_HTTP_BASIC;
$username = '******';
$password = '******';
$API = new ChargeOverAPI($url, $authmode, $username, $password);
$Invoice = new ChargeOverAPI_Object_Invoice();
$Invoice->setCustomerId(1);
$Invoice->setDate('2014-01-02');
$LineItem = new ChargeOverAPI_Object_LineItem();
$LineItem->setItemId(4);
$LineItem->setLineRate(29.95);
$LineItem->setLineQuantity(3);
$LineItem->setDescrip('Test of a description goes here.');
$Invoice->addLineItems($LineItem);
$LineItem = clone $LineItem;
$LineItem->setLineQuantity(2);
$Invoice->addLineItems($LineItem);
//print_r($Invoice->__toString());
$resp = $API->create($Invoice);
/*
print("\n\n\n\n");
	print($API->lastRequest());
	print("\n\n\n\n");
	print($API->lastResponse());
	print("\n\n\n\n");
*/
if (!$API->isError($resp)) {
    $invoice_id = $resp->response->id;