If you login to the portal website using your email address and password you can administer all your VPSs, change account details, place new orders etc.
If you login to the portal website using your VPS username and password you will only have access to manage a single VPS, no mention of VPSBlocks is made, and no ability to modify your account or order services.
How to start/stop your VPS
1. Go to https://portal.controlmyvps.com.au
2. Login using your email address and password
3. Click on 'VPS Management'
4. Select the VPS in question from the drop down list box