Abstract: Purpose This paper compares traditional and digital banks in nine categories of complaints and provides insights to improve complaint management performance. Design/methodology/approach A sample of the major Brazilian banks was defined, with four traditional and four digital banks. The grey relational analysis (GRA) method was applied as an analytical tool to compare the most frequent complaints of traditional and digital banks. The most critical complaints identified were considered to discuss potential improvements in complaint management using quality and service management system concepts. Findings The GRA method enabled the development of a ranking of nine complaint categories, considering the uncertainty involved in the data and differentiating between traditional and digital banks. The most critical complaint categories, regardless of business model, were "unauthorized charges" and "poor service," which were ranked first and second in the frequency rankings. Traditional and digital banks differed the most in the complaint category "unfair charge," ranking third and eighth in the rankings, respectively. Practical implications Managers from traditional and digital banks can improve complaint management performance by applying ISO 9001 and ISO 20000 concepts such as incident, problem, change, service level, availability, capacity, information technology service continuity and financial management. Social implications The study's findings can help bank managers improve service levels in the face of technological competition. Improving these organizations is an important factor for developing countries such as Brazil. Originality/value This paper reveals the differences between two business models regarding complaint management. It also considers a methodological approach to include the uncertainty related to customers' perception and subjectivity inherent to complaints Ver menos