Initially the City shall have a Department of Law, a Department of Finance, a Department of Public Safety and a Department of Public Service, and the Council shall provide by ordinance for the organization and duties thereof not provided for by this Charter. The Council may establish by ordinance new departments or divisions thereof, and, with the exception of the departments established by this Charter, the Council may combine or abolish existing departments and divisions as it may deem necessary, and may authorize one person to be the head of two or more departments or divisions. The Mayor may act as the head of either the Department of Public Safety or the Department of Public Service, or both.