Just a thought, I see you say that you've flushed the cooling system but did you take the rad out to give it a real good go? It may pay to reverse flush the radiator particularly if it's the original as they do silt up over time. I reckon it's also worth doing the heater matrix (pipes disconnected) then reflush the engine (thermostat out) to give it all a really good clean.
It'll only cost you a bit of time (apart from another bottle of antifreeze!) rather than keep replacing bits uneccessarily, might be worth a try?
Good luck.
Remember I suggested this before, I reckon its got to be worth a go.
Saw your suggestion alright and it was what had got me thinking about re-flushing it properly.
I flushed and reverse flushed the radiator with the hose, then put it back in and ran some radiator flush through it, I decided that for the €1.82 it cost in Halfords with the trade card that it had to be worth trying
I had to run it without the thermostat in to circulate the flush around the system, then flush with water (flushed rather dirty looking water out of it!) and run it with water and no stat to rinse it, rather than leaving it sitting on idle for ten minutes I took it out for a run and it didn't loose a drop of water, ran very cold obviously due to the lack of the thermostat, so I won't really know till tomorrow when I drain it and put the thermostat back in if its going to be ok or not.
