I'm engaging from PEM. Perhaps you can Google as there's many websites consolidating the different reviews from agencies :) good to book early tho!
Try to check this out: https://mummynanny.com/blog/29/HIRING+A+FREELANCE+CONFINEMENT+NANNY+%E2%80%94+CONCERNS,+RISKS+AND+THE+WAY+FORWARD
Pem, rec to engage agencies so in any event of you are unhappy with the cl, can change