@splendidisolation
Anyway what do you need an au pair for if you're free to stay at home spying on her 24/7?
This ^
@Sandro09
I can't fathom why you need an Au Pair either if you are at home all the time. As someone said, what is she doing for you? And why can you not do it if you're home so often? And why does a 10 year old need an Au Pair? 
As some people have said on here, YOU employed her, and your home is HER home. She has every right to be in that house as much as she wants. And if she is in her room all the time, why is she bothering you?
I ask again, what is she doing? Your child will beat school probably 8.30am til 3.30pm, and he apparently plays with his mates for the rest of the time, so he doesn't need childcare.
And in addition to you being there all the time, I am baffled as to why she is even there.
Re @mittens post above. Makes me wonder why people choose to have people in their house, (like people who take in lodgers and happily take their board money, and people who hire Au Pairs to do their grunt work and drudgery for them for minimum pay,) and then kick off and whine about their lack of 'privacy' when they are there.
Wonder if the OP is going to come back?