They suggest changing the structure of service quality models to a three-stage model: overall perceptions of service quality, primary dimensions, and Subdimensions (Figure 3).
This model was for evaluating service quality in retail store. Although multilevel propose a new structure, it needs to generalize for different areas and consider the effect of some other factors such as environment, price, etc.
In addition, there is lack of identifying attributes or factors that define the sub dimensions.