Create a sort by in Shop Page

Hi there, im trying to create a sort by from the brands plugin to sort in the WooCommerce shop page by alphabetical so All’s then Ben’s etc. I tried using the code below but I dont think I’m accessing your attribute correctly is you could help.

function theme_catalog_orderby( $catalog_orderby_options ) {
	$catalog_orderby_options['brands'] = __( 'Sort by brands', 'textdomain' );
 
	return $catalog_orderby_options;
}
 
add_filter( 'woocommerce_catalog_orderby', 'theme_catalog_orderby' );

/**
* Returns an array of arguments for ordering products based on the selected values.
*
* @uses woocommerce_get_catalog_ordering_args hook
* @return array
*/
function theme_get_catalog_ordering_args( $args ) {
  
  $orderby_value = isset( $_GET['orderby'] ) ? woocommerce_clean( $_GET['orderby'] ) : apply_filters( 'woocommerce_default_catalog_orderby', get_option( 'woocommerce_default_catalog_orderby' ) );
    if ( 'sale' == $orderby_value ) {
 
      	$args['meta_key'] = '_product_attribute[pa_brands]';
        $args['orderby'] = 'title';
        $args['order'] = 'ASC';
 
    }
 
    return $args;
}
 
add_filter( 'woocommerce_get_catalog_ordering_args', 'theme_get_catalog_ordering_args' );