The details of the functions conferred on the strata manager will be in their contract and can be pretty wide-ranging.
This is what the Act says:
(1) An owners corporation must appoint a strata committee of the owners corporation in accordance with this Act.
(4) If there is no strata committee of an owners corporation, the strata scheme must be administered by the owners corporation, but nothing in this subsection prevents a strata managing agent appointed under this Act from exercising any functions conferred on the agent.
52 Owners corporation may delegate functions to strata managing agent(1) An owners corporation may, by the instrument appointing a strata managing agent or some other instrument, delegate to the strata managing agent—
(a) all of its functions, or
(b) any one or more of its functions specified in the instrument, or
(c) all of its functions except those specified in the instrument.
(2) An owners corporation must not delegate to a strata managing agent its power to make—
(a) a delegation under this section, or
(b) a decision on a matter that is required to be decided by the owners corporation, or
(c) a determination relating to the levying or payment of contributions.
(3) A delegation may be made subject to the conditions or limitations as to the exercise of all or any of the functions, or as to time or circumstances, that may be specified in the instrument of delegation.
(4) An owners corporation may delegate the functions only if authorised to do so by a resolution at a general meeting.
(5) An owners corporation may, if authorised to do so by a resolution at a general meeting, revoke or vary a delegation under this section.
(1) A function delegated under this Division may, while the delegation remains unrevoked, be exercised from time to time in accordance with the delegation.
(2) Despite any delegation made under this Division, the owners corporation may continue to exercise all or any of the functions delegated.
(3) Any act or thing done or suffered by a strata managing agent while acting in the exercise of a delegation under this Division—
(a) has the same effect as if it had been done or suffered by the owners corporation, and
(b) is taken to have been done or suffered by the owners corporation.
(1) The instrument of appointment of a strata managing agent may provide that the strata managing agent has and may exercise all the functions of the chairperson, secretary, treasurer or strata committee of an owners corporation or the functions of those officers or the strata committee specified in the instrument.
(2) However, the chairperson, secretary, treasurer and strata committee of an owners corporation may continue to exercise all or any of the functions that the strata managing agent is authorised to exercise.
(3) Any act or thing done or suffered by a strata managing agent in the exercise of any function of the chairperson, secretary, treasurer or strata committee conferred on the strata managing agent in accordance with this section—
(a) has the same effect as if it had been done or suffered by the chairperson, secretary, treasurer or strata committee, and
(b) is taken to have been done or suffered by the chairperson, secretary, treasurer or strata committee.
It’s odd that the Act says there must be a committee, then tells us what the strata manager can do if there isn’t one.
But the crux of the problem is this: Is the strata manager making decision that are benefitting only some owners in a real way, or harming ths strata scheme in a real way. By that, I mean are you unhappy because you don’t agree with the decisions, or are they doing physical or financial harm to the scheme. If it’s the former, all you can do is try to persuade a majority of owners to support your view. If it’s the latter, and you can prove it, then you can go straight to the Tribunal (no mediation required) and ask for the appointment of a strata manager to run the scheme.