Customers not only make buying decisions as a result of what they hear from others but share those stories more widely when they have a positive experience with a brand. When a brand gets the strategy right, in creating a good complaints experience, it leads to a more robust and positive cycle of continuing advocacy.
Overall, NPS can be calculated by subtracting the % of your customers who are Detractors from the % of customers who are Promoters. NPS Detractors are much more likely to complain and churn than promoters, and you want to keep them not only as customers but convert them as advocates. An advocate becomes a promoter of the brand.