Using complex structure with SOAP - php

Question

The problem is that I cannot succeed to send an array of class through SOAP to a specific web service that I cannot change his structure.
Here below you'll see the schema of the Soap function:
http://www.elyotech.com/share/yoni/forum/developpeznet-soap.jpg
Here you'll find the code I'm corresponding to it:
$s = new soapclient($URL_WEBSERVICE,array('wsdl'=>true,"trace"=>true));
$params = new stdClass();
$params->loginInfo = new stdClass();
$params->loginInfo->UserName = 'username';
$params->loginInfo->Password = 'password';
$params->loginInfo->LanguageCode = 'en';
$params->reservation = new stdClass();
$params->reservation->EmailRecipient2 = 'yonia#yopmail.com';
$params->reservation->EmailRecipient3 = 'yonia2#yopmail.com';
$params->reservation->FirstName = 'Yoni'
foreach($extras as $id=>$extra)
{
$params->Extras[$id]= new stdClass();
$params->Extras[$id]->SelectedExtra = new stdClass();
$params->Extras[$id]->ExtensionData = new stdClass();
$params->Extras[$id]->SelectedExtra->Amount = 1;
$params->Extras[$id]->SelectedExtra->ID = $extra;
}
Here is the SOAP request that is sent:
<?xml version="1.0" encoding="UTF-8"?>
<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:ns1="http://tempuri.org/">
<SOAP-ENV:Body>
<ns1:CreateReservation>
<ns1:loginInfo>
<ns1:UserName>monusername</ns1:UserName>
<ns1:Password>monpass</ns1:Password>
<ns1:LanguageCode>en</ns1:LanguageCode>
</ns1:loginInfo>
<ns1:reservation>
<ns1:EmailRecipient2>yonia#yopmail.com</ns1:EmailRecipient2>
<ns1:EmailRecipient3>yonia2#yopmail.com</ns1:EmailRecipient3>
<ns1:FirstName>Yoni</ns1:FirstName>
</ns1:reservation>
</ns1:CreateReservation>
</SOAP-ENV:Body>
</SOAP-ENV:Envelope>
In this Soap request, I cannot find the Extras array of objects.
Do you have any idea of how I should create my object in order to send it correctly?