Argh! That is so frustrating! I'm sorry they're being so dense! I'm sending good thoughts and prayers to you!

Maybe you could send extra books or worksheets for him (assuming he likes worksheets)? My DD5 has been really enjoying the math literature books from the reading lists on the Living Math Blog. The blog has the books grouped by subject: Addition, Multiplication, etc. Maybe that could keep him happily busy and learning until they get a clue?