Guessing there isn't much discipline going on at home nor parents taking the adult role for that matter. In fairness to the parents lying so you don't turf the child is very normal behavioiur. Just like a kid they will lie when called up on the carpet because it speaks to their parenting abilities. But now that you know the truth you have two options. One is to let her go and the other is to ride her into submission, give her perameters and you might get a very cooperative child in the end. Two weeks isnt' long enough to see progress. I would be using my loud stern voice, making the child sit in the room we are in - not getting away with goign to a different room - just sitting at my feet till I say otherwise. It will take some being physical to let her know you mean what you say so if she gets up she is sat down again. The tone of voice has to match the severity so she will learn when you use that voice that she has overstepped. I probably would let the parents know that you are considering termination unless they also work with the child to control her anger. Do not let on you know that yes she does act this way at home. Then give it another two weeks and if at the end of that there is no improvement then time for her to become someone else's problem yes such as a centre where there are more adults so one of them can shadow her better.