$service = new DTSeBaySDKTradingServicesTradingService([
        'credentials' => $config['production']['credentials'],
        'authToken' => $config['production']['authToken'],
    'siteId'    => DTSeBaySDKConstantsSiteIds::GB
    ]
);

$req = new DTSeBaySDKTradingTypesGetMemberMessagesRequestType();
$req->StartCreationTime = new DateTime('2016-01-01');
$req->EndCreationTime = new DateTime('2016-07-07');
$req->MailMessageType = 'All';
$resp = $service->getMemberMessages($req);

$ret = '';

foreach ($resp->Errors as $err) {
    print($err->ShortMessage."<br/>");
}

foreach ($resp->MemberMessage as $msg){

    /* @var $msg DTSeBaySDKTypesMemberMessageType */
    $ret .= '<p>' . $msg->ID . ":" . $msg->Body . '</p>';
}

return $ret;