I cannot type CHinese on my computer. But I want to say: never feel touched by their tears. Only deal with what happened.
Maybe you can try this: tell your helper that you have marked down the number on each Octopus card already. If you still cannot find those cards, you will report to Police, and the Police can always trace down to whover is using the lost card. However, if you can find those cards again, you will not report to police. (I hope you have really recorded the number on each Octopus card to protect yourself.)
My bun bun told me that she has never used her mobile during the working time but she keeps her mobile in her jacket daily!
She always tears to say home sick and wants to leave but I asked her if she wants to go back to Philipine. She said no but just wants to leave to find another employer.