I'm getting somewhere:
exec("quota -u testclient | tail -1 | awk '{print $2}'", $out);
$os = preg_replace("/s+/", ":", $out[0]);
$t = str_replace(":{$user}", "", $os);
This is reporting correctly, but all values for mail, mysql and web are the same.
First I need to replace testclient with $user then add additional function to use quota for web usage only.