Poor girl
Sometimes that can happen if there's an instability of hormones and generally there are drugs to sort that out.
Sometimes its genetic, some people are just hairy.
And sometimes this happens after certain cancer treatments.
Dark haired girls obviously suffer most because the hair itself is more visable the darker it is.
For most it's the price of a decent family holiday every year at the beauty salon having electrolysis or ten family holidays for a course of Lazer therapy to sort it out once and for all.

I hope she's got a few quid.