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Sounds like it's worth a try then. I got a cheaper brand one ages ago to help with the black that gets on grouting and where I had a leak through the bathroom ceiling and it did help that (well, until the bathroom ceiling fell in!) but it smells so strongly of bleach, not sure why but the smell makes me feel sick, and my hands smell of it for ages afterwards. Doesn't help I only have a tiny bathroom. It didn't help on the tiles though.
I'll give the Dettol one a try. I've got some gloves so maybe I should spray it on with all the windows open so it's ventilated and I can hide downstairs then zap it in the shower, not able to bend or kneel to be able to scrub it much.
I'm so tempted to get a company in to do one of those blitz cleans then get someone in every couple of weeks to help me keep things ticking over. I've been meaning to for ages, just need to let go and get it done.
Thanks all.