Please could anyone suggest a cleaner to remove the black residue on the sealant between bath and tiled wall? This residue may be caused by lime scale from hard water and have tried most recognised brand names, but it's still there. Ta Muchly.
If the sealant is silicone rubber bath sealant and limescale remover does not work then the black substance is mould which has penetrated the silicone rubber and cannot be removed except by removing the silicone rubber. There are sealants available with mould inhibitors but the inhibitors don't last forever.
I have always used Dettox Mold and Mildew remover and it has worked fine. If as you say you have used most brands then the only way would be to do as jomifl says and remove it and put new around the bath. Make sure you use a silicone one and not the water based ones as these are much better and last longer. Then use a mould and mildew remover every month or so and wipe over to help stop it forming in the first place.
You could try Domestos,Grot Buster. It's a very thick bleach and the bottle has a thin nozzled top to direct the flow. You leave it on for a while and it bleaches the mould and no scrubbing even required! It worked well for me;-)