There could be many reasons why you are unable to access your cPanel, WHM or Webmail services, some examples of these are below. A notable mention would be:
IP Address Blocked in Servers Firewall (cPHulk, ConfigServer Security & Firewall, Imunify360)
This is the most common cause of the inability to access services. The best way to confirm is to utilise a device on a completely separate network (A Cellular or VPN Connection) and test again.
Other lesser-common issues that can still be applicable are:
Routing Issues
Domain issues (expired, suspended, etc)
No Account Exists
Billing Issues
Incorrect Server (DNS issues etc.)
If you cannot access a service, please lodge a Support Case through http://www.mysau.com.au or contact our Support Team on 1300 788 862.