Willow love don't bin it! I have had a mouldy BBB and now I can't tell which one it was! This mould was black and red and really nasty looking for a few washes but it did sun out eventually.
I also gave it a good nuke in the wash with dettol rinse and hot water to kill the fungus.

Jodi have you used longies? I think that may help especially if they are very hight rise.