DH had biro on his grey leather cat seats which he had put there, I got it off with lord sheratons leather wipes from tesco (waitrose have them too) Boy was I popular!!!
I think Methylated spirits is supposed to remove biro ink but I would try a bit on a place that doesn't show first.
Try painting the stain with a small artist's brush damped with meths?? this would keep any damage to a minimum.
dont panic! I used leatherclinic.co.uk
I called them and they were brilliant!
They are bound to have something for it - you would be amazed what you can restore!
If you want to get your leathers cleaned you should check out Spotlessleather.com. They have an online service which is really cool. Well priced and it gets shipped right to your door. Check them out. Mold is a very difficult thing to remove. They did hundreds of jackets from Hurricane Katrina.