Ive had 2 stalkers,

One sent me 130 txt messages before she got the idea (without me replying once)
The other one kept turning up at my house, threatend to go to work etc

Basically make your intentions clear ie-- Fuck off out my life i am not interested dont ever bother me again-- then totaly ignore them, they do eventually get the message.

if things get really bad, strangle the fucker and hide her in the garden