The customer is always right (even when they are wrong), until the brand no longer values the relationship with that customer. You should encourage your employees to communicate it as direct as that to the customer.
The brand should set out to make the customer deliriously happy - pre, during, and post purchase. That is the brand doing their part, in the unspoken relationship agreement, for the monetary exchange it expects in return.
There are a couple of questions, as a brand, you should begin to ask yourself before telling the customer that they are wrong and you will not honor their dispute.
1. Are you willing to lose that customer forever?
2. Are you willing to lose other customers, also?
When the brand is losing more money than it is gaining over the relationship's lifetime, just to make that customer happy, then (and only then) it is time to part ways. Otherwise, the customer is always right.
There are plenty of instances when the customer is clearly wrong, and the employee simply follows corporate policy telling the customer they are wrong.
Corporate policy is not the remedy. In fact, they all have it wrong. Corporate policy are rules that have become standard as a result of few instances in the past. They did not take the time to wholeheartedly think about the end of the means. They also wrote these policies before it was easier to spread information to the entire world. Corporate protocol needs a fresh perspective in this instance.
Think about how you feel when you are told that you are wrong. Then add the kerosene of we are not willing to help you as a result. Throw that on the flame of feeling miserable-it is a disastrous concoction. One that will leave a customer to gripe on social media, leave bad reviews, and tell all their friends of a miserable experience that they were engaged in.
Rewrite the policies. The policies can be overridden by management anyway, making the employee feel worse because they weren't entitled enough to help the customer initially. Instead, they had to go ask a 'higher up' if it were permissible. Now you went from making your customer upset to making your employee upset. Your employee is more important than your customer because they are your 'family'. Make your employees happy, so they can do the same for your customer. I recommend giving your employees the ability to make things right for the customer.
There aren't enough bad people trying to work the system to get over on a brand, to be concerned about losing a tidal wave of customers as a result of one customers unhappiness.
Today's lesson: Take the opportunity to learn from your customer and improve your policies for the rest of your brand's life. They are wrong ONLY when you decide that you no longer value that relationship with that customer, and are willing to deal with the overall consequences as a result.