Tailed by stranger from playground

This is scary I want to share this with you, evening my son and I head to playground. The gal usually is not local but can speak well in English and Malay, she often bully my son. She was there for like a week or two, she never says her name. She would go around playing with all kids she can find there. Then one day she tried to follow one gal in playground home because that gal wanted to go toilet then she says she also want to go. Lucky the gal says cannot her mom is at home, etc. Today the gal try to tail us home, I know she is behind me can her foot steps. I purposely stopped at road side saying to my son that his teacher not home yet. Guess what she stopped also and pretend like no see me but she is just three steps away from me. Earlier she asking me to borrow hand phone to her, no way since she is rude and no manner person. I just say no to her she then says she wanted to call her mom. I don't see her asking other lady that at playground there. She has been playing with many kids at playground she could simply ask anyone of the kids guardian there. She is not lost, she knows her way home. She sometimes cycle to the playground, she even buy soft drink and food there to eat. She could go find a public phone and make a call.