Page within the same slug as a taxonomy

I have a custom post type with the slug /buyers_guide/ with several taxonomies. For each section I wanted to have some sort of archive page listing the items within. For the buyers_guide I used the Taxonomy List Shortcode plugin to give a page with listed columns of terms from the taxomomy ‘brands’ rather than a standard archive. This works fine, however I would also like to have a page with a similar shortcode at /buyers_guide/brands/ (with buyer_guide as the parent) but when I try and produce this page I get ‘page not found’ even after refreshing permalinks.

Does anyone have any ideas how I can do this without it breaking like this?