Confusion over templates for Directory

Hi there - I've got myself in a muddle over templates for individual listings from Directory.

When there is a single-listing.php template in my active theme (Comet), it is used as the template for individual listings. But it doesn't display the custom fields associated with the listings.

Conversely, when then I disable the single-listing.php template, the page.php template is used. This DOES display both my content field and my custom fields. But since I want to play around a bit with how individual listings are presented, I need to be able to edit this file. Even if I knew what to do (and it's not obvious how I would do that), I would then be altering the template I need for other purposes.

So I guess my question is either:
* why should my custom fields and featured image not be showing up on my single-listing template? or
* how can I edit the page.php template?

It strikes me that the first option is the one to go for but without custom fields there isn't much point!

Thanks for any advice.