I called Monday morning during a heat wave and said that our unit was not cooling down as much as it should a hot afternoon.  They said they either could come out in the afternoon or the next day, which--considering we still had a/c and it was cool at night--was fine.  They did keep in touch (it was the next day), and I found the technician to be on-time and responsive.  (Some freon just needed to be added.)  The service call was $65 and the lb. of freon $25, so it was very reasonable.  He told me the techs work by the hour and not on commission like some companies, so they don't try to sell you something they don't need.  I definitely would use this company again.