Here is their website InstaGone Stain Remover
I too have a hybrid with a little mildew stains on the underside of the bulk ends. Used some bleach water, which did about 50% reduction, but this InstaGone might do the trick to finish the job.
A/C has stained the fabric with rust where it has dripped off the roof.
Maybe try some Simply Green cleaner too. I used that when we had a PUP....