I was looking at Electronic Water De-scalers, the ones where you wrap a cable around the incoming water pipe and plug them in.

I can't find any real evidence that they work, other than on the manufacturers websites.

Has anyone on here had any experience of them?

All I can say lots of buildings I have maintained in central london have them fitted. Wether they work or not is another issue. The only way to really stop it is water sofners that use salt, but they ain't cheap!