Considering further some aspects of (traditional) SLM that should be fixed.
The wrong way around
The practice of defining (mainly performance-based) KPIs is wide-spread, so wide-spread in fact that often the reasoning is reversed: Instead of measuring a set of KPIs that may have a positive influence quality, one often (implicitly) states that the quality of a service is defined as the outcome of these KPIs.
To give an extreme example: Suppose the weather is proven to have an impact on customer satisfaction of a call center. Is it rational to state that the wheather defines quality? Should the Service Level be calculated based on the weather statistics? I don’t think many managers would buy this.
On the other hand, when Service Levels are defined, one often finds quality defined as just one parameter like, e.g., ‘waiting time on-hold’ or ‘system uptime’.