Kilrock Multipurpose Descaler 5x Doses 400ml
I used to use Oust for kettle cleaning until I bought some of the Kilrock from Aldi when it was in their specials. Kilrock was way better, and although it says 5 doses, I usually do half a dose and that is plenty to leave the inside sparkling (I do have to do it every few weeks though as we are in a hard water area).
Worked pretty good in the loo too
I've used Kilrock for a few years now and I will never waste money on any other brand, the besy