Here I have a useful infographic that provides information to help you deal with negative comments about your business on the internet. I hope you appreciate it and please let me know about any other ideas. Via - https://www.awesomeresources.co.uk/negative-comments/
You would think this would be part of business 101, but the first thing an undisciplined business owners does is to jump online and defend their actions.
I liked the point that if you are wrong admit it. This is because people will trust you more as you are admitting for your mistake. There are very few brands or businesses that actually have admitted for their mistake and then seen an increase in their traffic.
I would say in general reach out to any dissatisfied customers and solve the problem. The best marketing you can have is happy clients and solving their problems is cheaper than NOT doing so plus buying traditional marketing.