I have been tutoring SAT and PSAT Prep a very long time, and I am almost positive I can improve your child's official test score.
The SAT demands that students be able to read and comprehend complex passages, understand basic mathematical concepts (not just mindlessly memorize formulas), and be consciously aware of grammatical rules (not just go by what "sounds good").
I've tutored quite a few adults, and what shocked me was how many had a BA/BS and still couldn't "read." What I mean by reading is understanding what you've read, not just saying the words to yourself. I see the same problem with high school students, so I think SAT prep is good for more than just raising test scores.
The SAT is serious business. A great SAT score can get your child into the college or university of his or her choice, and it can save you a lot of money. How? Colleges and universities want the brightest students (they think the SAT is a very good indicator of intelligence), so they give merit scholarships in order to lure great young minds. For example, one student of mine had a good, solid academic record and leadership experience. She had a good SAT score but, with some tutoring, got a great SAT score. She ended up getting an $80,000 merit scholarship to the college of her choice (she also got financial aid on top of that).
I have helped students get into MIT, NYU, Stanford, the UCs, and many other notable colleges and universities. Some of these kids got large merit scholarships to help foot the bill. With the right tutoring, your child could get in a very good college, but it is pretty rough out there. Perhaps a third of the admittees to college are admitted because of affirmative action policies or because they are great athletes. High GPAs and test scores don't guarantee anything.
Have you heard of "grade inflation"? If you haven't, you are definitely out of the loop. There are lots of kids with 4.0 or better GPAs. California is full of kids with straight A's. I have been to schools in which over three-fourths of the kids were on the Honor Roll (these were failing or faltering public schools). I had one student who had a 4.9 GPA (AP and honors classes are worth more than regular classes; thus, an A could be worth more than 4 points) but a very low SAT score. I tutored her a few times, but I couldn't help much because she wasn't very bright (just being honest; can't fault someone for being honest). Colleges don't want those kids; colleges want the brightest kids. Fortunately, most kids are capable of adding around 300 points to their SAT total, with the aid of a good tutor.