Remember writing actual letters with pen and paper? You sealed the letter in an envelope, slapped a stamp on it and dropped it in the mail. Then you waited. It could take weeks, even months, to get a response. We were, I suppose, a more patient species then.

Some call that bygone era “the good ol’ days,” but I don’t miss writing letters, and I sure don’t miss waiting a month for a response. On the other hand, instantaneous communication has its drawbacks, too. Carrying a smartphone makes me available to anyone who has my number, anytime, anywhere, whether I want to be available or not. If I don’t reply to a text immediately, I feel like I’m being rude, even if the text is nothing but a “cute” video of a cat with the hiccups.

Fortunately, those who know us well don’t mind if we’re slow to respond to a text or Facebook post. Restaurant customers, however, have different expectations. Yet again and again I see too many customer comments—and, more importantly, complaints—go unaddressed on pizzeria Facebook pages.

I recently visited the Facebook page of a certain pizzeria chain with 100-plus locations. The reviews section teemed with negative comments, and five out of the first 10 starred reviews were one-star ratings. Granted, the remainder were all five-star reviews, so we shouldn’t read too much into these assessments. There will always be complainers. What worried me was that, as the negative ratings and angry comments piled up, no one at this chain was bothering to respond to them. Not even so much as a “Thanks for the feedback.”

This failure to respond is, in a way, a response, and it’s one of the worst I can think of. It suggests that 1) the chain uses Facebook strictly as a sales tool, not as a means to engage with its customers; and 2) the chain doesn’t really give a hoot if its customers go home dissatisfied and angry.

I wish this was an unusual case, but I see the same problem all over Facebook. Too many pizzerias use social media to put out their sales messages while turning a deaf ear to the messages—both positive and negative—that their patrons send back.

And if you think potential customers don’t pay attention to online reviews, you’re mistaken. According to the 2014 Local Consumer Review Survey, a study conducted by the United Kingdom-based BrightLocal, 88% of consumers say they trust online reviews as much as personal recommendations, and 72% say positive reviews make them trust a local business more.

So how hard is it, really, to take the time to click “like” or better yet post a quick “thank you” on every positive review you receive each day? And when a disgruntled customer slams you in this very public forum, doesn’t it make more sense to respond quickly and offer to make it right in that same public forum, for all to see, rather than ignore the complaint?

You can’t control online reviews, but you can use social media to show that you care about your customer’s concerns. You need to devote some time to it or assign the responsibility to someone who can. It’s not a passing fad. As a restaurant marketing tool, social media is as essential as your signage and your menu. Use it wisely, and reap the benefits. Use it foolishly, and you may pay the price in lost business and revenue.