alt Hacker NewsNot asking the customer because you're afraid they'll tell you they're upset is a good indicator that you should do it more, and fix the issues.
You can ask the customer enough times that unreasonable customers or surveys are averaged out.
A good question might be "why are you upset?"
Isn’t it a running joke at this point that if you do what customers ask instead of focusing on the highest quality of service you get worse outcomes and the customer is still unhappy?