Rapid proliferation of the distributed energy resources (DERs) poses operational challenges for the low-voltage (LV) distribution networks in terms of thermal overloading of the network assets along with voltage limit violations at the connection points. A number of market-based and direct control approaches have been widely developed to tackle these challenges with different objectives. While most of the techniques aim to solve the problems separately, an integrated and efficient method is missing to handle such correlated issues simultaneously. In this study, a unified approach combining local voltage control mechanism with a centralized congestion management scheme is proposed by utilizing an agent-based hierarchical architecture. The feasibility of the proposed approach is validated with a simulation analysis for a representative Dutch urban LV network considering up to 100% penetration of solar PV and electric heat pumps (HPs). The quantitative analysis reveals that, local voltage control strategies can essentially aid mitigating thermal overloading of the network assets. Thus, integrating a local voltage control method with a coordinated congestion management mechanism can enhance the system flexibility while maintaining the network constraints and the comfort levels of the consumers simultaneously.