One of the most common ways for a company to better understand its customers is to gain information about them through surveys.
When conducting surveys, companies are able to do a lot of things. They can get access to customers' contact information. If a customer has a bad experience, a company can learn how it can improve and prevent this from happening again. If the customer had a positive experience with the company, the company can learn what it's doing right.
Surveys can help make your customer's experience better. Even If there is little you can do to make improvements to the customer's experience, at least you're giving your customer an opportunity to voice their opinion and be heard. The customer should always feel that you're listening.
If you have an irrational customer, don't ignore them. If you do, you are only making a bad situation worse. Irrational customers can be the loudest customers and if you treat them fairly and let them vent, then that irrational customer becomes more recognizable as a person who is irrational. Other customers will recognize your attempts to provide good customer service and dismiss this irrational person. Do not ignore any of your customers.
Hopefully your company is taking advantage of surveys and if not, it's never too late to get started.