Como posso modificar o namespace da resposta assim:

resposta antiga:

<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
   <soap:Body>
      <ns2:GetAmountResponse xmlns:ns2="http://ws.dsi.otn.com/dab">
         <etat>0</etat>
         <montant>500.0</montant>
      </ns2:GetAmountResponse>
   </soap:Body>
</soap:Envelope>

nova resposta desejada:

<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
   <soap:Body>
      <GetAmountResponse xmlns="http://ws.dsi.otn.com/dab">
         <etat>0</etat>
         <montant>500.0</montant>
      </GetAmountResponse>
   </soap:Body>
</soap:Envelope>

Eu quero remover o prefixo namespce ns2.