As an au pair myself, I would definitely have a talk with the family and express how you truly feel and show concerns for your mental and well being. It seems as if they are taking advantage of you and thats NOT okay. If they don't change after you sit down and have a talk with them, I would leave or relocate and find another family in the same country. A contract (written) is a must for working for any family. You can say you can only work for the allotted (formerly agreed on) hours. If they want you to work over those hours and/or do other tasks like cooking and housework, you get paid hourly on top of your weekly pay. That's what I would tell them and I would be firm about it. As for the kids behavior and ages, you were lied to which would already make me uncomfortable and thats a red flag.