Here are some suggestions for what you can do:
1) To get rid of the mold, put the bag inside-out in direct sun for a day. Then apply a lemon juice and salt solution to the fabric and keep it in the sun until it dries.
2) To keep the mold from coming back and to prevent it from growing, wash the bag fairly regularly. Dry the bag, while open, on top of the dryer or outside in the sun, weather permitting.
3) Make sure to remove the ice pack from the bag as soon as the bag comes home so that the ice pack doesn't sit in there any longer than necessary.
4) Don't store wet bags in a closed space where it is easier for mold to grow.
Mold and staining are not covered under our warranty, as they are not a manufacturer's defect. We don't treat our bags with anti-mold or anti-staining treatments, as they can be quite toxic.