Spray mould stain with a mixture of vinegar and water (2 parts vinegar: 1 part water), and work it in with a scrubber. Let sit for 20 minutes or so. Then put your item into the washing machine with 3 cups of vinegar; turn your machine on with a cold water setting; allow it to fill, but turn the machine off to soak your stain for a couple of hours. Then, put in your Diva Laundry Balls and wash as usual! This should remove the stubborn stain and the smell that accompanies it.