My nephew didn't get the grades he needed for the Uni course he wanted to take. The grades were good enough for another Uni that like your son he wasn't very keen on. He rang the preferred one on results day and the person he spoke to had met him at the open day and he had shown real interest and potential, and he got in. Not saying that this always works, but if he goes and meets someone linked with the course, then if he is just short, it may still work for him. Good luck