When someone leaves a bad review or a negative comment on your business’s social media page or other online assets (GMB for example), you need to do whatever it takes to solve the issue. Even in person via a phone call or a meeting if it really escalated.
But when that doesn’t work, and sometimes it doesn’t, that’s ok.
The most important thing you need to keep in mind is that when you reply to interactions with a negative tone, you are replying to all the hundreds, thousands, sometimes dozens of thousands of pairs of eyes who are reading your response and also judge you by it.
You need to be determined to get it right because it’s the right thing to do, but also because your response will determine what these other people think of you, not just this one person whom you might not be able to convince either way.