Healthcare organisations' responses to concerns and complaints often fall short of the expectations of patients and staff who raise them, and substandard responses to concerns and complaints have been implicated in organisational failures. Informed by Habermas's systems theory, we offer new insights into the features of organisations' responses to concerns and complaints that give rise to these problems. We draw on a large qualitative dataset, comprising 88 predominantly narrative interviews with people raising and responding to concerns and complaints in six English NHS organisations. In common with past studies, many participants described frustrations with systems and processes that seemed ill-equipped to deal with concerns of the kinds they raised. Departing from existing analyses, we identify the influence of functional rationality, as conceptualised by Habermas, and embodied in procedures, pathways and scripts for response, in producing this dissatisfaction. Functionally rational processes were well equipped to deal with simple, readily categorised concerns and complaints. They were less well placed to respond adequately to concerns and complaints that were complex, cross-cutting, or irreducible to predetermined criteria for redress and resolution. Drawing on empirical examples and on Habermas's theory of communicative action, we offer suggestions for alternative and supplementary approaches to responding to concerns and complaints that might better address both the expectations of complainants and the improvement of services.