I use bathroom cleaner on mine but you can buy specific stuff to get rid of it though I don't think it's a green alternative. Lemon juice, white vinegar and bicarb sometimes works with some elbow grease. Just depends how much work you want to put in it. After you do get them sparkling, just clean them every week and just wash the limescale off with soap a few times to prevent it building up.
I think the stuff to get from the supermarket for limescale is called Viakal. And it works but do it soon as the more it builds up the harder it is to get rid.
"CILLIT BANG" used daily keeps taps, basins, baths & stainless steel sink looking pristine. If you have a build up of lime, use "LIMELITE! Gel & a stiff toothbrush, leave it on for a few minutes then scrub & scrape off the heavy stuff with the plastc handle.
Daisy.....it should do I cleaned the bathroom glass shelf and window with a damp cloth with some of the vinegar on it and its sparkling! I just bought the cheapest white vinegar from Tesco it was only 44p :)