ombudsman

A man who investigates complaints and mediates fair settlements, especially between aggrieved parties such as consumers or students and an institution or organization.

A government official, especially in Scandinavian countries, who investigates citizens’ complaints against the government or its functionaries.

An appointed official whose duty is to investigate complaints, generally on behalf of individuals such as consumers or taxpayers, against institutions such as companies and government departments.

A designated internal mediator in an organization whose duty is to assist members with conflict resolution and other problems and to serve as independent consultant to recommend changes to policies or procedures to improve organization effectiveness, efficiency, and humaneness.

a government appointee who investigates complaints by private persons against the government