SAT - testing accommodations

My son is a junior in HS and has been certified by our local county school system as LD since 2nd grade. He is dyslexic and has long been diagnosed with “auditory processing and visual-motor integration deficits.” He now attends a small private HS where he has an IEP (as he did in public school) that includes testing accommodations. We submitted a request to the College Board for accommodations for the PSAT/SAT last year and received 50% extended time vs. the 100% we requested. The College Board also denied our request to allow our son to mark directly in the test booklet vs the bubble sheet, stating that his “block design” score wasn’t low enough for this accommodation.
Our son took the PSAT last fall and 50% extended time was (as we feared) clearly insufficient for him. So this year we requested the additional accommodations that the College Board had denied last year. Through our son’s school we submitted extensive additional supporting documentation from a licensed clinical psychologist (who has tested our son several times) as well as supporting letters from our son’s math and English teachers. We also detailed his long LD history and prior testing accommodations. Two months later the College Board sent us a notice listing the original accommodations again. They provided absolutely no explanation for denying the additional accommodations we requested. In fact, the notice doesn’t even acknowledge that we made such a request. I intend to press the College Board for an explanation regarding the denail of our request for additinal accommodations and then utilize whatever appeals process is available since we have already provided ample documentation in accordance with the College Board’s requirements.

My question is - Has anyone succeeded in obtaining additional accommodations from the College Board that were initially denied (esp. 100% extended time testing or marking answers directly in the answer booklet)? Also, has anyone been through an appeals process with the College Board with regard to either of these accommodations? And, if so can you offer us any advice in that regard?

Thanks in advance for your help.