This is the code. I've multiple servers, with Obsidian it not work anymore, does not change the quota, while with a server running Onyx 17.8.11 it works fine, so the problem is with Obsidian 18.0.38
$request = <<<EOF
<packet>
<mail>
<update>
<set>
<filter>
<site-id>$id_server_site</site-id>
<mailname>
<name>$account_name</name>
<mailbox>
<enabled>true</enabled>
<quota>$new_quota</quota>
</mailbox>
</mailname>
</filter>
</set>
</update>
</mail>
</packet>
EOF;
$response = $client->request($request);