Surely you have bylaws that state how meetings must be called and noticed to members. Also, there must be a president of your board. A board member simply cannot call up the property manager and give instructions. There are typically contracts or bylaws that state who manages contractors, such as the property manager. If he is in violation of the bylaws, then nothing he does, like pass motions, etc., would even stand because he isn't properly noticing the meetings, and potentially a quorum isn't being reached.