Suggest Treatment For ADD And Oppositional Defiant Disorder

My grandson is 15 and a sophomore in high school. He is having problems in school because he has special needs in the area of reading. He has ADHD and ODD, according to his doctors. His reading level is about 3rd to 4th grade reading level. No one has been able to tell us why he can't progress in reading. He is a really good kid at this point, but I can see some signs of his giving up. He almost failed his biology class because he needed a lot more help than he was getting at school. My question is what I can do to find the right reading program to help him read at a high enough level to pass his classes.