Mold and Mildew stains

Michaela

So we lived with my parents for a short amount of time this past year. I was planning on reusing my daughters infant car seat for her sister, due February 19th. We stored all of our stuff in their barn and the car seat developed a lot of mold. I've cleaned and scrubbed with detergent, I know the mold is dead but the stains remain. Any good tips to get it out? I've read about borax, but haven't tried it.