I had this 15-year old living nearby who was really starting to
get fresh with me. Sometimes she would message me at 1 am asking me
to meet her under her block 'just to talk' when I had lessons the
next morning.
Even after telling her that, she would continue to bug me with her
messages. I simply switched my handphone off.
The next day I told her straight in the face that she was
irritating me with all her incessant messaging. I told her that if
she didn't cut it out, I would go to her parents.
Problem solved.