Pricing: Customers are very sensitive to pricing and any increase in the same can lead to termination of relationship.
Service: Customers have varied options to choose from and a slightest dip in service standards will lead to customers' defection.
Product: A bad product can lead to customer dissatisfaction leading to customer defection. A simple example of a new car introduced in the market without much emphasis given to after sales service and bad quality spares can lead to a bad publicity and word of mouth. This is worst publicity for an organization and will spell doom.