Whenever it shall appear that any telephone utility is failing or omitting, or about to fail or omit, to do anything required of it by law or by order of the commission or is doing anything, or about to do anything, or permitting anything, or about to permit anything, to be done contrary to or in violation of law or of any order of the commission, an action or proceeding shall be prosecuted by the regulatory staff in any court of competent jurisdiction in the name of the Office of Regulatory Staff or the State for the purpose of having such violation or threatened violation discontinued or prevented, either by mandamus, injunction, or other appropriate relief and in such action or proceeding it shall be permissible to join such other persons or corporations as parties thereto as may be reasonably necessary to make the order of the court in all respects effective.