bluetobits,
Here in Cyprus, we have really hard water also. I bought an electronic scale inhibitor, maybe 4 years ago while on a trip back to UK. I saw it advertised on ''Ideal World'' and was on offer (can't remember the cost) so ordered one.
Called ''Scale Wizard''
They work!! it has almost eradicated the lime scale in our kettle and other water heating appliances significantly, as i suspect it has in the pipework. Never get scale build-up on shower heads and taps now either.
Last year, i got my son to buy another for me, and bring it with him on his visit, for our rental villa. Since it's installation limescale reduced within a couple of months. ....Get one, ...i'm sure it will reduce your problems with lime scale at the very least!!!