Bedford Managment Company

I have a unit in Park Slope rented out to tenants, and the property is managed by Bedford Management Company. This management company really hasn't been very responsive since I bought the unit and rented it out. I've asked them about a few things, and they don't really get back to me. I've asked them to fix something in the common area, and they said they would but still haven't. This time it isn't a big deal (its just a humidifier in the common storage area) but I'm worried about when something bigger happens, like roof leaking, or heating not working, etc...What are my options here? Am I allowed to get my own guy into the common area to fix things? Do I just have to keep calling and be a pain in the ass?