My thermostat went haywire this week; does not hold a program and "hold temp" doesn't override. It has a mind of its own. Put in new batteries twice, but still get a readout "low battery"; tried to reprogram but instructions on unit don't seem to work...or I don't know how to interpret the instructions, but have had no issues with this unit since it was installed. Tried reprogramming again yesterday and it worked for a very short while, then reset itself and turned off the AC....help!