Community health centres in South Africa play a crucial role in providing essential healthcare services to underserved populations. However, their effectiveness and reliability are subject to scrutiny. We employed a Difference-in-Differences model to compare changes in service delivery metrics before and after implementing quality improvement interventions at selected health centres. Data were collected from electronic health records and validated through cross-sectional surveys of patients. A significant difference was observed between the control and intervention groups, with an effect size of approximately 20%, indicating that the implemented improvements had a substantial impact on service delivery reliability. The findings suggest that systematic quality improvement measures can significantly enhance the reliability of community health centre systems in South Africa. The use of DID models provided robust evidence to support these conclusions. Health authorities should prioritise continuous monitoring and periodic reviews of community health centres to ensure ongoing improvements and maintain high service standards. Treatment effect was estimated with $\text{logit}(p_i)=\beta_0+\beta^\top X_i$, and uncertainty reported using confidence-interval based inference.