dialogue: Sam: Where are you?
  Tilly: Just leaving school now?
  Sam: What have you been doing? You said you would be home for 4!
  Tilly: Yes had to go for detention
  Sam: I asked your mum if that's what had happened but she said she hadn't got a text
  Tilly: They are useless. They are supposed to tell your parents if you get a detention.
  Sam: How long will you be?
  Tilly: About 40 minutes
  Sam: OK.. I'm going back to mine - phone me when you are home.
  Tilly: OK - see you soon.
summary: Tilly was supposed to come home by 4 but she got a detention. The school was supposed to inform her parents about it, but didn't do it. Sam is coming back home. Tilly will be home in 40 minutes. She will call Sam then. 