Q: How do you know when you have truly won over a customer?
A: When they laugh!
After you have listened, encouraged venting, offered empathy and reassurance, see if you can get them to laugh.
"Only 15 percent of sentences that trigger laughter are funny in any discernable way. Instead, laughter seems to bubble up in conversations when people feel themselves and are responding in parallel to an emotionally positive circumstance." The Social Animal, by David Brooks.
So you don't need to be a comedian, simply focus on moving that conversation from the dark side to the happy side.
Let me know how many people you make laugh today!