I am attempting to paint a room in our house and am having a difficult time. This was a kid's room and the previous owners had some bears professionally painted on the walls that are very DARK. I have applied 2 coats of Kilz and that doesn't appear to have done much. I have also tried sanding and some of the paint comes off, but not where they painted a solid dark color. If anybody can direct me to a product that may help remove this paint or any suggestions I would greatly appreciate it.

If you want to see the mess I am dealing with, let me know and I can send a picture. That may help you get a better idea.

Thanks in advance.