Open your wp-domain-checker\lib\DomainAvailability.php file and look for co.za
ensure that co.za and all other ZACR domains use the correct whois servers
“co.za” => array(“coza-whois.registry.net.za”,”Available”),
“net.za” => array(“net-whois.registry.net.za”,”Available”),
“org.za” => array(“org-whois.registry.net.za”,”Available”),
“web.za” => array(“web-whois.registry.net.za”,”Available”),
“durban” => array(“whois.nic.durban”,”Available”),
“capetown” => array(“whois.nic.capetown”,”Available”),
“joburg” => array(“whois.nic.joburg”,”Available”),