being harassed

for over a month and a half i have been getting calls from international readers league looking for my sister i guess she gave my number as a referance. I have told the lady atleast two dozen times my sister doesnt live here,I have called the office 3 times to complain to people,they have reassured me i wouldnt get anouther call. tonight at 8:30 the woman called again when i told her ive talked to her boss and if she dont leave me alone ill get her fired she responded by telling me off in nasty language.Im going to see what i can do about sueing them for harassment i mean 45 days of this is more than enough.NEVER GIVE OUT NUMBERS FOR A REFERENCE IT COULD COST SOMEONE ALOT OF AGGRIVATION!!!