Limit a query to a specific 'type'

I am using a plug in, which stores tickets as posts (Awesome Support Plugin)

in the plugin classes, there is a function to restrict the tickets loading in the admin panel, basically to show tickets to agent where the tickets are assigned to.

now I want to pimp this function a little bit to have super visors for this agents and show the tickets to them but not all of the tickets, just the tickets which are related to them.

basically I want to recreate the wordpress filters in the posts page for a parameter called ‘type’.
I found this ‘type’ param from the url address bar of the browser when I set the filter in the WP backend panel.

here is the function:

/**
	 * We prevent the agents from seeing
	 * other agents tickets. This also
	 * applies to admins if the option
	 * is enabled.
	 *
	 * @param (object) $query The page's main query
	 * @return (object) Updated query
	 */
	public function restrictTickets($query) {

		global $pagenow, $current_user, $user_ID;

		if( current_user_can( 'administrator' ) && wpas_get_option( 'admins_see_all', 'no' ) == 'yes' )
			return;

        // so support admin can see all the tickets
        if( current_user_can('see_all_tickets') )
            return;

        // so support managers can see all the tickets in their field
        if( current_user_can('see_related_tickets') && isset( $_GET['post_type'] ) && 'tickets' == $_GET['post_type']){
            if( $query->query_vars['post_type'] == 'tickets' ) {

               // this is the field which I should set, and unfortunately does not work! --->>>>
                $query->query['type'] = 29;

                return $query;
            }
        }

		if( is_admin() && isset( $_GET['post_type'] ) && 'tickets' == $_GET['post_type'] ) {

			if( $query->query_vars['post_type'] == 'tickets' ) {

				$query->query_vars['meta_key'] 	 = WPAS_PREFIX.'assignee';
				$query->query_vars['meta_value'] = $current_user->data->ID;

				/* Fix wrong post count */
				add_filter( "views_edit-tickets", array( $this, 'fixPostCount' ) );
			}
		}

		return $query;
	}

can anyone help me, please?!