The cost of influencing a new customer rapidly increases and exceeds the cost of retaining existing customer. Thus, companies tend to be more concerned with customer retention. Keeping their current market share is one of the important tasks for companies. Understanding why customers complain and switch from one company to another help companies to retain their customers. One of the reasons consumers engage in negative responses can result from dissonance experienced after purchase. The concept cognitive dissonance has been studied widely in the literature of consumer behavior. However, there are few studies discussing the relation between cognitive dissonance (its dimensions) and consumers' complaint responses. This study adopts the 22-item scale of Sweeney et al. (2000) in order to evaluate consumers' level of cognitive dissonance after purchasing a smartphone.This study offers three dimensions of cognitive dissonance -emotion, wisdom of purchase and concern over deal-as the predictors of external information search and consumer complaint responses. This study tests whether cognitive dissonance has significant effects on consumers' search for external information, and in turn, on consumers' complaint and switching intention. The empirical analysis was carried out based on the data gathered by 400 smartphone users, living in Ankara, the capital city of Turkey. The survey result was analyzed by using Partial Least Squares (PLS-PM) analysis method. The results reveal that when consumers feel emotional and rational inconsistencies after smartphone purchasing, they need information from external sources (such as asking friends, relatives, other stores), and this information search behavior leads to negative consumer responses as complaint and switching intention.