add_action('woocommerce_simple_auctions_before_place_bid' , 'custom_max_single_bid_limit' ,10 , 3);  
 
function custom_max_single_bid_limit($product_id, $bid,$product_data)     {
    global $product_data;      
   
 
    if (($bid - $product_data->auction_current_bid) >= '100') {
 
        wc_add_notice(sprintf('Your bid is bigger than  max  single bid amount', 'wc_simple_auctions'),'error');
        $product_data = FALSE;
        return false;
       
 
      }  
           
 
}