i have got rid of a lot of the muck, but its the hard water thats done the damage, i have ordered some white vinegar spray which should come today/tomorrow - i couldn't get any at Dyas.
I just use it and remove straight away Emmie but I’d say the water here isn’t hard, perhaps leaving it for 15 minutes till the enzymes cut into the stain?
thanks Bobbi, will leave it on for 30 minutes and see if i can't shift the anti slip mat outlines, that's where the hard water accumulates. i wash the anti slip mats regularly. i had a shower and washed off a load of gunk with your telescopic draper squeegee.