Child Care Centre Neglect. what do I do?

i have an almost 3 year old son who is autistic and has attended the same child care centre 3 days a week for over a year. At first it was great the staff were lovely and very accommodating. he had a great carer who he formed a close bond with and was progressing rapidly. The last few months however things have not been going well. the centre's numbers have dropped resulting in my son losing his carer. (which i was never notified of) he was also bumped up from the toddler to kindy room even though he wasn't ready. His new educators are having trouble with him. he hasn't formed any kind of bond with them at all. and now cries every time we pull into the car park.
his therapist have reported a decline in his abilities and that he acts 'lost' when he is there. my son has several therapists, 2 of which visit the centre fortnightly to offer advice and support to the staff on what and how to care for him and to help him be involved. but it seems whatever they suggest never gets implemented. One of the staff members seems to have no time for my son what so ever. and is very blunt and unapproachable when ever i try to ask her about my son's day.
Things just seem to be getting worse.

a month ago one of the staff members picked him up and he threw himself backwards resulting in him being dropped and he smashed his head on the shed. He had a massive bruise/swelling which was never treated by the staff and they did not tell me about the accident until i had already collected him and at first told me he walked into the shed. 3 phone calls later i got the correct story. i have had several talks to the director and she always says the same thing. that she will speak to the staff and she agrees its unacceptable.
last Monday when i went to collect my son (an hour earlier then usual) i could hear his cries as soon as i opened my car door in the car park, i peered through the fence to the playground to see my son pacing back and forth tears streaming down his face crying like id never seen before. i watched for a few minutes to see if anyone was going to help him. 2 staff members stood less then 3 metres away chatting to each other completely ignoring my boy. I immediately grabbed my boy and stormed out. Today i had another meeting with the director who was extremely apologetic, agreeing it was unacceptable and neglectful. and that she had had words with one lady in-particular who is from another country who stated 'she is not trained to deal with a child like that, and back in her country children like him get locked up!' i was mortified. she had also been holding his against his will to keep him in time out when he was naughty. i had a good chat and the director and i came to some good solutions (for several other issues as well), the director said my son could be moved back to the toddler room and would not be cared for by that staff member anymore and that she had been given her final warning. she would also organize him a new carer.
but then at 3pm today i get a call saying my son has smashed his head on a pole and to come and pick him up. again another big bruise and swelling. final straw for me! my son is a very easy going child not clumsy at all.. he is completely non-verbal and a year behind in development and cannot tell me what is going on. i just do not trust this centre anymore. i asked for a copy of his all his accident reports and none could be found!

i used to love this place, my son used to love going there. there are some lovely girls that work there and my boy does have a bond with the ladies in the toddler room. i just don't know what to do. i have to work and my son has to go somewhere. i have no-one else who can look after him for me. i am waiting to hear back from the head office about a formal complaint, i don't know what else to do. what more i can do to make sure this never happens again to my boy or any other child? i have rung all the local centres and no-one has vacancies on the days i need. i feel so horrible and guilty sending him back there. we are moving an hour away in 6 weeks he already has a new centre where we are going. am i a bad mum for sending him back to this centre if he can be in the toddler room away from this other lady, as its only for a few weeks? and how do i go about taking my complaints further? feeling so sad and guilty.