Our CM927 unit developed faults - eating up batteries every two months, temperature getting stuck - if it was on it stayed on and the house overheated, if it was off it stayed off and the house froze. Problem was, it was installed by a third party 3.5 years ago. I contacted Honeywell through their website http://www.honeywelluk.com/ explaining the problem. That was on Monday. On Thursday a courier knocked at the door with a brand new replacement unit, completely free of charge. Now that's what I call customer service - no hassle, prompt, and bending over backwards to do the right thing. Thank you, Honeywell !!! 
