I've used General for three years now for my own home as well as a rental property. Recently they were called to our rental because our 15-yr-old furnace fan was loud. I didn't hear back from them until I received a bill in mail 3 weeks later totaling $1,1000!
From our tenant, we discovered that they did fixed the noise, but who in their right mind does a $1,100 repair on a 15-yr-old furnace without asking?!!! And it wasn't an emergency, since the furnace was still operational. I tried to talk with someone, to no avail, so finally just sent in a letter complaining, with no response.
I don't doubt that they did the work they claimed, but I don't think they care about their 'little' clients.