Gee that doesnt sound right. I would definately speak to someone.
The ACECQA is the government body that regulates and grants accreditation to childcare centres. Get in contact with them and they should investigate, do checks on the centre and the staff to make sure they are comlliant. There are laws as to how much space for how many children, staff ratios etc.
It sounds like an awful environment. Did the children seem happy? If not, definately put that in with your complaint.

ETA- I did a Google to check before I posted (because I can never remember what its called) and discovered that the NCAC has closed in Dec 2011 and been replaced with the above.