If I remember correctly, WeChat has a locator feature based on GPS, so presumably you have this function turned-on? Do these women send the message in Chinese or English?

Doesn't WeChat also have a function that blocks your details from anybody who is not in your 'contact' list? I don't know if you are using the international version, but the Chinese version is 'regulated' and monitored so that certain words are on a stop-list and explicit messages may not be published. I'm sure you'll correct me if I am wrong about this.