DOMParser

Dom.Document doc = new Dom.Document();
doc.load(xmlstringdata);//Here xmlstring data is from the above XML shown above 
//Retrieve the root element for this document.
 Dom.XMLNode env= doc.getRootElement();
      //system.debug('****'+env);
       dom.XmlNode  Body=env.getChildElement('Body','Schema URL');
    //system.debug('&&&&'+Body);
        Dom.XMLNode  GetActivationInformationResponse=Body.getChildElement('GetActivationInformationResponse','Schema URL');
    //system.debug('NEW'+GetActivationInformationResponse);
    Dom.XMLNode  GetActivationInformationResult=GetActivationInformationResponse.getChildElement('GetActivationInformationResult','Schema URL');
 //system.debug('TRIII'+GetActivationInformationResult);
String name =  GetActivationInformationResult.getChildElement('ATMFee', 'Schema URL url').getText();
system.debug('*****'+name);