Results showing random unrelated graphics

Sometimes our search results show random images or graphics with an entry. Other times no images are shown.
Is there any way to set if and when images are shown? And more importantly, is there any way to make sure the image shown is actually relevant in some way to the result it is paired with?

Here is a screen cap that illustrates our problem

Would the premium version offer better control on this?

Our site, if you need it, is pa-vendors.com, and the Relevansi search box is in the footer right now.

https://wordpress.org/plugins/relevanssi/