As you will now be aware, sandstone is very absorbent so care should be taken when attempting to remove stains as more damage can be done than harm.
There are many products out there on the market however choosing the correct one can be an art in itself. We are in the business of carrying out such work and use specialist products however if you google 'redwine stain sandstone' you will find such products.
My only advice is to contact the technical department prior to purchasing and ask questions about their product. Any worthy company will not only stand by their product but also go out of their way to offer you helpful advice on how to use the product, the guaranteed results and suggest a suitable sealer to help prevent this happening again.