Repair existing Search functionality

We publish a magazine in print. We have developed a site that encapsulates the published content into a site. The site is built on WP and is fully bespoke. It functions in two parts: Editorial Content and a Supplier Directory. The biggest issue with the site is 'search'. The Editorial content and the directory operate in the same environment i.e. One wordpress site. The directory utilises the same search engine as the editorial content but the two are kept seperate (i.e. The directory does not show up Editorial in its results and vice versa) The developer used an off-the-shelf plug in and the result is undesirable - However I should be clear. The search functions in the editorial section are satisfactory. They are not within the directory. Unfortunately, this is not a skill this developer seemed to possess. I have looked at other plug ins such as WPSearch and Relevanssi and these may do the job - however, since the site is bespoke, I suspect they will have to be customised. as well. As a typical example, if a search is A P Photography, it will not find this supplier but will list the entire contents of the directory. Furthermore, I do not have filtering options for 'Best Match', by 'Locality, 'Most recommended' etc.. There are other repairs to be made but this is the most imminent. The site can be viewed at [login to view URL]