Consumers often face considerable frustration when purchasing high involvement products characterised as structurally and/or semantically complex. This is exacerbated in online buying situations where the limitations of computer mediated communication come into play. To help overcome this problem this paper proposes expanding existing research streams and adding aspects of communication theory such as social semiotics to gain insights into consumer needs online. These insights go beyond the major limitation of current online consumer behaviour modelling which has focussed on predicting the probability of online purchase for standardised search type products like books and CDs by examining complex purchases. This paper reviews the needs of consumers in a complex purchase process and proposes a research program, based on a fusion of current research practices and communication theory, to the enable development of a responsive system-based dialogue between vendors and consumers.