I would seriously consider a new day care. You can report them to the State Licensing authority for day cares: http://ccld.ca.gov/PG487.htm
You can hire a lawyer and see if that makes them pay attention. I don't know how serious the scratches are. The problem with kids this age is that often their rendition of events is unreliable in the legal sense. I certainly wouldn't let my kid go back.
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