I'm sorry but if the shoe was on the other foot I would be doing anything to see my children and man the hell up and accept that he is going to be in my life for the next 16 years and accept that I have to deal with him and the sooner things are cleared up the better!
Exactly what I was saying. But you cannot force him to do anything. You'll only be breaking your own head on a stone wall to try.
I am not allowed to know when he is off work or free
This is NOT YOUR PROBLEM. You set the schedule that works for you. If he has a problem he can contact you to make other arrangements that suit you both ahead of time, not at the last minute. The point is that you aren't waiting around on tenterhooks for him to decide what he wants. It may be correct that it's not your business to know exactly what he's doing (i.e. if he's at work or if he's with his gf). But it is your business to know ahead of time when your child will be with him. You have a life to live, too.
when he has ds I am not allowed to contact him to ask how he is or anything like that because it is none of my business apparently
Unfortunately, I think I agree. It is 'his' time with the the child and it could be disruptive. I don't think you'd appreciate if he called you constantly to 'check up' on you to see if your son was 'ok' in your care or 'upset' because he wasn't there. If you don't feel your child is safe with his father, then you need to decide whether he should have him unsupervised.
don't like using his parents because in the past when we have done this information has not been passed on correctly and I also don't feel that having his parents as the middle man is correct because it is his parents they don't think anything is wrong with this picture and that I am the bad guy stopping their son seeing ds!
Then you need to suggest another intermediary. I'm sure I'm wrong but it almost sounds as if you want to force him into dealing with you when he doesn't want to. Is there a reason why you want to remain in contact with him? Sorry if I appear rude, but do you still have feelings for him or do you feel that you should still have a place in his life?