The members of the council shall not direct or dictate the appointment of any person to or his removal from office by the mayor or any department directors. Except for the purposes of inquiring or receiving information or advice, the council shall deal with the municipal departments and personnel solely through the mayor and no member of the council shall give orders to any subordinate of the municipality. The council shall have the power to investigate any part of the municipal government and for that purpose to compel the attendance of witnesses and the production of documents and other evidence.