Helpdesk plays an important role in a company to maintain customer satisfaction. To ensure help-desk's solutions effectiveness, the service quality must be evaluated and monitored periodically. In this study, we evaluated the quality service of help-desk service by finding out the sigma level to discover the root of the problems. We used complaint data from a help-desk service of an IS/IT department in a public university between 2016 and 2017. We performed sub-methodology DMAIC (Definition, Measurement, Analysis, Improvement, and Control) in Six-Sigma and adopted COBIT 5 framework in the improvement phase to enhance the service quality. The SIPOC diagram shows that the help-desk service was at a high-level. The DPMO value in 2016 was 30.153 and it rose to 80.155 in 2017. It caused the sigma level to drop from 3.37σ in 2016 to 2.90σ in 2017. From the Pareto chart, we know that complaints regarding SIAD and network account for as much as 51.72% and 23.82%, respectively. Therefore, the cause of the problem must be found, according to the Pareto principle. The root causes of this problem are categorized into policy, procedure, plant/technology, and people. Meanwhile, COBIT 5 presents solutions to policy and procedure problems by providing best practices on standard operating procedures through domain DSS02 Manage Service Requests and Incidents and domain DSS03 Manage Problems. The combination of Sig-Sigma and COBIT 5 is able to evaluate the service quality of the help-desk service. The method in this research can be used to evaluate service quality in other organizational divisions.