Agents are listed by publish date. Most recent are listed first. Change publish date to change order.

agent order

To change order in code and make agents go alphabetically, go to agents_list.php

Instead of

$args = array(
'cache_results' => false,
'post_type' => 'estate_agent',
'paged' => $paged,
'posts_per_page' => 10 );

Add 2 more options: orderby and order

$args = array(
'cache_results' => false,
'post_type' => 'estate_agent',
'paged' => $paged,
'posts_per_page' => 10 ,
'orderby' => 'title',
'order' => 'ASC' );