The purpose of this paper is to present the approach to knowledge acquisition and computer reasoning support in a call center environment. The common problem in such environments (especially in technical call centers) is that the call operators are usually just the interface to the experts inside the company. They often lack the detailed technical knowledge in the field of study, especially when they are newcomers who just started with their job. For this reason we developed the expert system (ES) that is able to obtain needed expertise from technical staff and it is able to assist less technically versed operators to provide feedback to customers and acquire the knowledge needed to fix the particular customer problem. The prototype implementation of the ES was built for the national roadside assistance call center which is focused on car fault diagnosis.