Services are subject to constant change and variation, leading to continuous redesign and improvement. However, service changes shouldn't be disruptive by requiring radical modifications or by altering the way that business is conducted. In this article, we discuss a causal model of service changes that addresses the effects of both shallow and deep changes. This article is largely based on concepts and definitions found in previous work. The definitions used have been revised and amended on the basis of formalization and compatibility analysis, prototype implementation, comparison with functionality offered by open standards, and an empirical in depth investigation using an industrial strength case study.