Climapro rf battery usage?

I have a Glowworm hxi system controlled by the Climapro rf programmable room thermostat. It is now 2.5yrs old & has suddenly decided to eat the batteries in the Climapro. I am replacing the 3 AAA batteries every week. I have gone through 4 sets of Duracell batteries in a month now. The used batteries are low on power. The heating system functions okay. I haven't introduced anything into the house that could be interrupting the rf signal.
Any clues