parse wsdl xml response with namespace into array - code igniter php using nusoap

I have some trouble to parse the xml response from wsdl to array using php. this is the xml respone from wsdl

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://ift.tt/sVJIaE">
   <SOAP-ENV:Body>
      <ns0:Header xmlns:ns0="http://ift.tt/1zOlfbf"/>
      <ns0:GetCustAccTypeAndBalanceRs xmlns:ns0="http://ift.tt/1xlWDke" xmlns:jms1="http://ift.tt/1sGvYiH">
         <ns0:customer_type>2</ns0:customer_type>
         <ns0:balance_amt>51300000</ns0:balance_amt>
         <ns0:account_status>1</ns0:account_status>
         <ns0:account_no>P20111117400700667035625</ns0:account_no>
         <ns0:account_type>3</ns0:account_type>
         <ns0:customer_id>28650</ns0:customer_id>
      </ns0:GetCustAccTypeAndBalanceRs>
      <ns0:CommonResponse xmlns:ns0="http://ift.tt/1xlWDkg" xmlns:jms1="http://ift.tt/1sGvYiH">
         <ns0:ResponseCode>00</ns0:ResponseCode>
      </ns0:CommonResponse>
   </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

and this is my code in CI PHP

$client = new nusoap_client('http://ift.tt/1zOlh2T', true);
                $client->soap_defencoding = 'utf-8';
                $client->header = 'Content-Type: ext/xml;charset=UTF-8';
                $client->useHTTPPersistentConnection();      

                if($client->fault)
        {
             $text = 'Error: '.$client->fault;
                         print_r($text);die;
        }
        else{
                        if ($client->getError())
                        {
                                $text = 'Error: '.$client->getError();
                                print_r($text);die;
                        }else
                        {
                                $ns= array('v2' => 'http://ift.tt/1xlWDke');
                                $content ='<v2:GetCustAccTypeAndBalanceRq>
                                                 <!--Optional:-->
                                                 <v2:msisdn>6287877035625</v2:msisdn>
                                          </v2:GetCustAccTypeAndBalanceRq>';
                                $mesagge = $client->serializeEnvelope($content,false, $ns,'document','literal','');
                                $result = $client->send($mesagge,'/Services/jmsEP/opGetCustAccTypeAndBalance'); 
                                $res = array(
                                                'customer_type' => $respon['GetCustAccTypeAndBalanceRs']['customer_type'],
                                                'balance_amt' => $respon['GetCustAccTypeAndBalanceRs']['balance_amt'],
                                                'account_status' => $respon['GetCustAccTypeAndBalanceRs']['account_status'],
                                                'account_no' => $respon['GetCustAccTypeAndBalanceRs']['account_no'],
                                                'account_type' => $respon['GetCustAccTypeAndBalanceRs']['account_type'],
                                                'customer_id' => $respon['GetCustAccTypeAndBalanceRs']['customer_id'],
                                                'ResponseCode' => $respon['CommonResponse']['ResponseCode'],
                                                'ErrorMessage' => $respon['CommonResponse']['ErrorMessage']
                                        );
                                $amount = $res['balance_amt'];
                                
                                return $amount; 
                        }
                }

Can someone tell me how to parse the wsdl xml response to array? Thank you so much