In order to access the hosting control panel through cp.yourdomain.com the domain will need to be registered and pointing to our nameservers, if either of these options isn't true then this address will fail to load.
You can access the hosting control panel from the Manage Hosting Packages page in your Eco Web Hosting control, the direct link is
https://www.ecowebhosting.co.uk/cp/managehosting
Alternatively, if you wish to access directly then please use
https://stackcp.com