Must thank Ryanair - the low-cost airline - for showing us all how NOT to handle comments from customers (and potential customers).
Having people who take the time to contact you about potential flaws in your website, product or service is a great honor. It shows they care. And if you listen to them, there's a good chance you'll improve your service. (And if you improve your service, there's a good chance you'll make more money.)
Ryanair doesn't seem to agree, as you can read in this article.