see http://www.zabbix.com/consulting.php

at the end, there's a sentence "Commercial Support is paid via a fixed cost annual contract, covers only questions related to troubleshooting specific Zabbix problems, to coaching how to install and configure Zabbix and provides fixes for source code bugs."

there's something wrong, as it reads like this :
"Commercial Support... to coaching how to install and configure Zabbix"