The literature argues that the alternative outcomes of a customer either ending or continuing a struggling relationship not only depend on the determinant factors or switching barriers, but also on the essential nature of the relationship. This paper adapts a broad social exchange framework to business-to-business (B-to-B) exchange relationships, and explains "unjustified persistence" or the tendency to remain involved in a B-to-B relationship that is dissatisfying overall. Specifically, the paper extends the knowledge on the mediating factors that influence the likelihood of dissatisfied B-to-B customers who have complained, and considered switching, to continue purchasing from their existing service provider. Data was collected online from 376 businesses using a key informant approach, and analysed using structural equation modelling software AMOS 7.0 with maximumlikelihood (ML) estimation. The findings support all the hypothesised relationships and imply that the potential loss of special privileges, if the customer were to switch from their current service provider, are related to a feeling of dependence on, and calculative commitment to, the service provider. The mediation mechanisms also imply that sunk costs are more related to dependence or calculative commitment than repurchase intentions, and that dependence or calculative commitment continues to play a role in generating customer outcomes.