PHP Soap Parameter issue

I am attempting to connect to a SOAP service and am unsuccessful in retrieving the data. I get the structure but no data. The person at the provider has sent me the corrections to my request however, I am not sure how to change my request to accomplish this. Below is my code and the request I am sending and the corrected request they are suggesting. Can anyone help with how to modify?

Thanks!

CODE:

$URL = 'http://addressof?wsdl';

$client = new SoapClient(null, array(
    "location" => $URL,
        "uri"      => "http://givenbyprovider",
        "style"    => SOAP_RPC,
        "use"      => SOAP_ENCODED
    ));

$return = $client->__soapCall("getEsnInfo",
   array('esn' => '12345678')
);


MYREQUEST:

<?xml version="1.0" encoding="UTF-8"?>
<SOAP-ENV:Envelope
xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
xmlns:ns1="http://xxxx"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"
SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
<SOAP-ENV:Body>
<ns1:getEsnInfo>
<param0 xsi:type="xsd:string">12345678</param0>
</ns1:getEsnInfo></SOAP-ENV:Body>
</SOAP-ENV:Envelope>

SUGGESTED REQUEST:

<?xml version="1.0" encoding="UTF-8"?>
<SOAP-ENV:Envelope
xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
xmlns:ns1="http://xxxx"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"
SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
<SOAP-ENV:Body>
<ns1:getEsnInfo>
<param0 > <esn xsi:type="xsd:string">12345678</esn></param0>
</ns1:getEsnInfo></SOAP-ENV:Body>
</SOAP-ENV:Envelope>