Service Oriented Architectures (SOA) enable dynamic integration of Web Services (WS) to accomplish a user's need. As such, they are sensitive to user errors. This article presents a framework for mitigating the risks of user errors due to changes in the service delivery context. The underlying methodology incorporates usability in the design, testing, deployment and operation of dynamic collaborative WS, so that the error-prone elements of the User Interface (UI) are identified and eliminated. The methodology incorporates Statistical Process Control (SPC) of Web Service Indices (WSI), obtained by a Decision Support system for User Interface Design (DSUID), in which the users are elements of the control loop.