According to the European Commission, the objective of EU competition rules is enhancing 'consumer welfare'. In EU competition law, however, 'consumer' means 'customer' and encompasses intermediate customers as well as final consumers. Under Article 102TFEU, harming intermediate 'customers' is generally presumed to harm 'consumers' and where intermediate customers are not competitors of the dominant undertaking, there is no requisite to assess the effects of conduct on users further downstream. Using advances in economics of vertical restraints and, in particular, non-linear pricing, this article shows that there are instances where the effect on 'customer welfare' does not coincide with the effect on 'consumer welfare' and the presumption can potentially lead to decisional errors. Thus, if the law is to serve the interests of 'consumers', the Commission should reconsider this presumption and its interpretation of the 'consumer' in 'consumer welfare'; otherwise, it remains questionable whose interests EU competition law serves.