To find your current plan details including tariffs you need to go to Hi [FirstName]> Account Settings > Property and plans > Your Plans > [Plan Name] > Edit
I would never have found the information at the current location without assistance.
A better and more intuitive location for a link to this would be on would be on the Overview page in the Online Services box where you have Add energy plan and Change energy plan. A simple link there to My energy plan would be really helpful!
I saw mention that the same functionality was being considered to the App, please locate it it somewhere intuitive like the Help > Plans and Rates section there, and not in the Account > Settings section.