What brand and model is this thermostat

The model is a "Thermostat programmable hebdomadaire castorama", as shown in the below image (found on the Internet). A closely-related manual (not the exact model, but the same functionalities) used to be available under address http://www.castorama.fr/media_aux/810203_a1.pdf, but not anymore. My own copy is here.

I don't know if you ever got this worked out or not, but I'm in the same boat. Bought an Ecobee3 and I have the RA832A relay. It doesn't appear as though it has any sort of C wire capability.

Awhile back before I bought the unit or knew what my boiler was using in any sort of detail I reached out to Ecobee and this is what they said (I was planning to merge the boiler and AC into one thermostat as they are two separate now).

They said:

The boiler would use Rh and W. The AC would use Rc C G and Y

On their support site they have an article talking about what you can do if you don't have a C wire and one of the options was use a transformer and isolation relay.