Firstly, I have tried vinegar and lemon juice as recommended frequently. Fortunately I'm not in an area with Limescale! Used ordinary commercial cheap bog standard shower cleaners of course without success
Its not fair to call it really "dirty", as it isn't, as no mould and has been cleaned lightly and not used much. But without realising it, over years, tracks of previous soaps and shampoos have built up which no amount of elbow grease and vinegar/soaps will budge.
Looking back it needed cleaning after nearly every use. Didn't really notice or realise - one of those things where you think, "oh I'll give it a proper clean one day": hindsight a great thing.
so it "looks" reasonably OK, till the light shines on the tiles and the plastic glass and the greasy solid tracks are all too visible, and its not really clean and nice.
so I'm looking for a product that will really dissolve these tracks so it looks spiffing and shiny
