[Plugin: WordPress SEO by Yoast] Multiple Categories/Taxonomies Problem

Have a fairly complex WordPress site that uses multiple categories and multiple countries (which are a custom taxonomy) to display “submissions” – which are essentially just custom posts.

At the furthest point of drilling down through cats and countries, the URL ends up like this; http://www.thebrief.co/_preview/?submission_country=united-kingdom+london&submission_category=see+art-and-design

and, it kinda messes the WordPress SEO plugin up – the title ending up like this; “SITE NAME Categories: see+art-and-design; Countries: united-kingdom+london”

Now obviously we kinda want the title to be something like “Art and Design in London, United Kingdom”

Any ideas here???? Pretty desperate at the moment as going to be launching in the next day or so…