Ejemplo
<?xml version="1.0" encoding="UTF-8"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
   <soap:Body>
      <Execute xmlns="http://api.decidir.com.ar">
         <Security>XXXXXXXXXXXXXXXXXXXXXXXXX</Security>
         <Session xsi:nil="true" />
         <Merchant>12345678</Merchant>
         <Operation>Anulacion</Operation>
         <EncodingMethod>XML</EncodingMethod>
         <api:Payload xmlns:api="http://api.decidir.com.ar">
            <Request xmlns="">
               <NROCOMERCIO>12345678</NROCOMERCIO>
               <NROOPERACION>CV142668740924-1</NROOPERACION>
            </Request> 
         </api:Payload>
      </Execute>
   </soap:Body>
</soap:Envelope>