Error pages in Sonata not working as expected

I am trying to create my 404 and 500 pages using Sonata for Symfony. It has created the 2 internal routes at the backend and when I go to any page that should show an error page, it looks like it is showing my 'internal' template that most of the site uses, however the 'page' var is not available so the template just throws an error.

I changed the not found error page in the backend to look at a different template yet it still looks at the same internal one.

I am not sure how i'm meant to edit the pages when there is no where to put any data and where the page var is not available to me in the twig.

Has anyone managed to get this working or can provide some more info on how to do it, the documentation in sonata for error pages isn't great!

THanks

Kevin