Thanks for your replies. I am aware that they expect me to be a housekeeper too - now - they just didnt mention it in the role before. When they complained about my cleaning, they said they would employ a cleaner and take some of my pocket money away if I dont want to do it, so there definitely wont be any money on top of what I am earning even after the discussion.
Speaking of which, I mentioned my pocket money, because frankly, I dont know how much I should be earning in London - I just saw it's higher than what most family offered and I expected to spend more time with kids than a regular au pair. However, my neighbour's au pair said she gets extra cash for cleaning and does it only on Fridays for a couple of hours and earns more than what I do.
The last minute plans are not last minute to them, they just tell me about them at the very last minute. I feel like he is more organised and knows about things, but she is the one who deals with childcare and forgets.
When it comes to transport fares, last night we had to take a bus home from an activity because I didnt have enough money for the taxi (spent more than expected on stuff to school) and came home quite late to which they said I need to keep more cash on hand and didnt reimburse what I bought/didnt give me any extra cash.
I have no contract and doubt they pay tax for me because I asked to put my money straight into the bank account and they said no, because they'd have to claim tax return or something like that.
Honestly, the reason why I asked about it on here was to see if I am being a brat about my situation, or if they are indeed threating me unfairly. The way they treat me makes me feel humiliated, patronised and offended (especially when they questioned my cleaning after 4 hours of polishing the house!). They said they are very happy with the childcare, but host dad always finds something wrong with what I do without telling me their (silly) rules beforehand, which creates negative environment at home (kids get in trouble for not telling me what they can or cannot do - they say I let them - I am the bad guy) and it makes me anxious never knowing whether my work is up to their standards or if I will be told off again (ham okay for afternoon, not okay for breakfast; girl can wear shorts to school, but trousers only if they touch the ground completely - but they are still longer than shorts?; homework to be done only by the kitchen table, not in the lounge etc).
I had a 'real job' before which I quit to do something I actually enjoy before going back to uni, so I decided to look for another 'real job' and leave after Christmas. That would give them enough time to find someone else and I could still hang out with kids on weekends if I want to.