Problems with Honeywell wireless room stats, any advice?

[Pannacotta]

I have a relatively new system boiler and wireless room stats (3 years old).
The house is zoned, so there is a room stat for upstairs and one for downstairs.
The downstairs stat is losing characters. I thought it was the battery as it showed a low battery error message, but after having put in newly charged batteries three times it's clear that this isn't the issue.
I have looked on Google and see on Amazon that this is a common problem with this stat (CM927).
I cant afford to replace both units - they cost over £100 each, is it possible to replace one but not the other or will I need to pay a heating engineer to link them both back to the boiler?
Or can I buy a new, different stat for downstairs only?

And advice please as I cant use the heating at the moment and it's getting very cold at night (large and draughty victorian house...)?

TIA

I had one like that which failed twice in 5 years. After that we switched to a non-digital type and it was still working when we moved a year later.

Are you sure there isn't an override option (maybe a button on the programmer marked 'override') to enable you to turn your heating on and off at the programmer bypassing the wall thermostat? It's not a long term solution but it would enable you to use the heating.

"losing characters" sounds like the display is worn out. LCD displays do that with age. It should still work though.

I don't like wireless stats, they give another two potential points of failure. Certainly you can change it for a wired one, the Honeywell CM907 is very good. You will however have to have a cable run from the boiler to wherever you decide to put it (preferably in your main living room as long as it does not have another sourcer of heat such as an open fire). For economy you could get a simple wired stat with a knob which will be much cheaper, but do please have the cable run in 3+E so you can change to a better one if and when you fel like it.

btw instead of rechargable batteries, I would recommend alkaline or lithium cells.