The credentials to your control panel are not the same as your customer zone. These details can be found in the welcome mailer that was sent upon activation. We are able to resend these details upon request.
The second method is by logging into your customer zone first and follow these steps:
1) Click on "Services"
2) Click on "Manage Product" next to the service you wish to access.
3) Finally, click on Login to Control Panel to access your domain management interface.
You should now be redirected to your control panel.