Log onto your account.
On your Dashboard, click on 'Services' at the top of the webpage. From the list of options given, click on 'My Services'.
Find the service you want to access Plesk or Webmail from and click the three dots beside it on the right-hand side.
Another list of suggestions will pop up. Click on 'View Details'.
Near the bottom of the screen of the left-hand side, there will be a section tiled 'One Click Login'. From here you can access both Plesk and Webmail via the links shown in the section.