How do we change strata managers?

I am pretty dissatisfied with our strata manager. He is a local real estate agent and I think has managed the building for quite a while, there are things that haven't been done from one AGM to the next. My current and serious concerns have taken several phone calls to get any answers and I am still not satisfied with the response.

I think there are 3 owners in the block of 12 and I now believe it is time for a professional strata management company. How do we go about this when the strata manager is the only one who knows and has access to the owner details?