Попробуйте что-то вроде этого:
$string = <<<XML
[your SOAP response above]
XML;
$xml = simplexml_load_string($string);
$results = $xml->xpath('//fault/ErrorDetail');
$err = $results[0]->xpath('./preceding-sibling::ErrorMessage/text()');
echo $err[0]."\r\n";
foreach($results as $result) {
echo $result;
echo "\r\n";
}
Вывод:
Validation error
Deceased's family name at birth must be in capitals
Deceased's Family Name must be in capitals