Wordpress search plugin compatible with ''wp property' plugin

WP Property ( http://usabilitydynamics.com/products/wp-property/ ) is fully featured real estate plug in but their search functionality is not good enough (it does not have a filtering function) I am therefore looking someone who can either 'improve' the search that comes with the plugin, alternatively develop a new and more advanced search plugin that work with the other plugin.
In brief, the problem with the existing search functionality is that if I have properties listed different cities in Spain and France, if I select France as country, the search options for 'City' still include cities in both France and Spain. A more detailed brief will be provided on request.