"All you need to do is use a soft sponge and gently wipe the solution, leaving it on the tap to dissolve the limescale deposits for two minutes. Once the time is up, rinse thoroughly with water." ...
This everyday kitchen ingredient is acidic, which allows it to break down and dissolve limescale, making it easier to clean without resorting ... to "remove impossible tap stains".
Boil and then discard this last lot of water to leave your kettle in squeaky-clean ... out your tap water for filtered or softened water can also play a part in cutting down limescale build ...