The good thing is that it's a lot easier and quicker for us to flag them up as fraudulent than it is for them to keep making them, and the more they make, the more easily they are seen to be pure scams. These three are pretty well clones of each other, so they have no credibility, and once a potential victim has seen a fake site, they'll look much harder at any others they see, and they'll know what to look out for.
All a person has to do is to Google for information on any site before parting with their money, and if they are listed here, they'll save themselves from losing their cash. If they're unsure, all they have to do is ask.
I hope this burst of new sites might be a sign that they're hitting a lean spell. Our free advertising must be helping in that respect.
Non-EU citizens should go here to find out about obtaining a visa to work as an au pair in the UK
http://www.ukvisas.gov.uk/en/doineedvisa/
Whenever payment is requested by Western Union you're dealing with a scammer