In times of high market transparency and rapidly evolving technologies, customer requirements are constantly rising and long-term customer loyalty is hard to achieve. Therefore, enterprises have spent enormous efforts on professionalizing their customer relationship management (CRM). Complaint management holds a key position in CRM, since it helps restoring customer satisfaction and repurchase intentions. \ \ This teaching case deals with the development of a complaint management process at a German fleet management company using PROMET BPR, a well-established method for business process reengineering (BPR). Further, the introduction of a software that supports the newly introduced complaint management process is described. The teaching case presents valuable findings for practitioners, planning to establish professional complaint management procedures within their own company, as well as students, learning how a scientific grounded BPR method can be applied in practice. \