This article was written by Ilya Pozin and published on Inc.com

Every company deals with bad customers. People complain because they want something for free, because they had a bad day, or because they just feel like it. However, not all complaints are created equal, and not all customers who complain are bad.

As Bill Gates said in his book Business @ the Speed of Thought, “Your most unhappy customers are your greatest source of learning.” The majority of unhappy customers don’t enjoy being unhappy: Something about the company, product, or customer service experience made them that way. By listening to the valid grievances of these customers, businesses can identify their shortcomings and turn unhappy shoppers into satisfied brand advocates.

Turning Customer Frowns Upside Down

According to research from Walker, customer experience will outpace price and product quality as the top competitive differentiator for sellers by 2020. People know they can find good prices online, and they rely on reviews to figure out which products are worth their money. When it comes to experience, though, it’s up to individual businesses to provide memorable, personalized experiences that keep customers coming back.

At Microsoft, Gates’s words haven’t faded into the past. The tech giant still practices what its founder preaches–even with resellers, vendors, and service providers. Microsoft actively trains and assists its partners in marketing and customer service, passing on its years of knowledge and experience to help smaller companies create more positive customer interactions.

Great customer experiences depend on an open dialogue. While happy customers are great, unhappy customers show businesses where they need to improve to keep the experience positive. Follow these steps to turn negative customer feedback into a force for good.

1. Listen closely

Nothing frustrates upset customers more than canned responses. Irritated people want to be heard, not placated. Demonstrate to customers that their complaints are important by listening to them and logging the results. If multiple people complain about the same thing, something is wrong. Whether that’s misaligned expectations of the product’s function or an employee who rubs people the wrong way, repeated complaints deserve serious investigation.

2. Evaluate the product

Don’t assume the experience is to blame before evaluating how the product itself relates to the customers’ displeasure. Is this particular product defective, or does the offering include a critical gap that prevents some customers from using it effectively? Would a different product do for the customer what the initial product could not? Answer these questions first to see whether the problem goes deeper than human interactions.

3. Gather more information

If unhappy customers seem to have valid concerns but can’t provide enough information to nail down the specific issue, don’t act for the sake of action. Send out surveys to learn about the kinds of changes customers would like to see. Email or call people who have had bad experiences and talk to them about what went wrong and what they would like to see next time. Not only does this clarify the issue at hand, but these communications can also bring unhappy customers back into the fold by demonstrating that the company is willing to change.

4. Implement changes

With customer information in hand that points to a concrete problem, act swiftly to prevent bad experiences from happening in the future. Sometimes, that means creating more detailed product instructions to prevent confusion. Other times, it means letting go of employees who refuse to make customer satisfaction a priority. Keep team members incentivized to provide good experiences by linking bonuses and recognition to great customer care.

Unhappy customers don’t have to stay that way. By listening to their complaints, evaluating possible improvements, and addressing their concerns, businesses can win back unhappy customers and prevent their negative experiences from becoming the norm.