I would recommend highly a company called River Rock Academy in Dallas. I have used them for the past 3 years for my daughter (who is now a UD freshman) and my son who is a 9th grader. They actually are a specialized school, but do a lot of in-home tutoring and mentoring, catering to the specialized needs of each child.
They come to my house and have many different teachers (who I believe are all certified). Both of my kids are now happy and successful students and much of that credit goes to River Rock.
They are Christian based with very kind and compassionate teachers. Can't say enough good about them.