Fitting a room thermostat

I am intending to fit a room stat to a Heatline Compact S30 combi-boiler. Currently the boiler is not working and Heatline are refusing to honour the guarantee unless certain installation faults are made good. Due to the mains wiring needed to install the reciever unit for a wireless reciever and the cost I'm starting to favour the idea of drilling and chasing out the wall. I'm fairly sure that the heatline wiring for a stat is two wires, currently these are one long very thin white wire in a loop. I believe that you cut this wire and connect it to the room-stat to over-ride the current programmer on the boiler. I was told by their engineer that the programmable timer was not enough, and that the pump would still be cycling constantly. Is this correct? It's a 24hr dial with lots of little switches. I would have thought that when set to off for a period it would stop the boiler. I could be wrong, but due to the thinness of the wire I suspect that it's a two-wire milivolt system so wont be compatible with a lot of thermostats. Am I right in thinking that a battery powered thermostat model would be what I am looking for? If I did go the wireless route, I would need to get 230V mains power to the reciever unit, but would I be able to attatch this to the boilers thermostat wires? Is the current wire loop, once cut, sufficient to connect to the thermostat or do I have to solder on new two-conductor thermostat wire? Can I splice extra wire onto the existing lengths if they are too short? Basicaly any help or advice would be brilliant. I'd consider getting a sparky in to do the wiring, but if I can DIY it all the better. I've fitted new lights and stuff before and it seems I could do this job without having to touch mains electricity. Any thoughts or advice on types of thermostat or best installation practice?
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