Also assume you have an extra sim card so could contact them anonymously and that your friend was happy for you to take any non-violent action you deemed appropriate.

For the purpose of this entirely hypothetical exercise we'll assume the stalker is someone she met once a few months back who's subsequently sent three texts a day (some describing accurately what she's doing at that moment) and has tried calling her from a variety of different numbers.

So what, if any, action would you take?