Harassment for somebody elses debt

I've been receiving constant phone calls from Norman Bisset & Associates Group ***) looking for my ex-husband, we have been divorced for nearly 8 years. I've asked nicely, I've been rude, I've begged and pleaded but they keep on phoning me and has now resorted in phoning my husband as well, who gives you the right to dig into people's phone records to obtain most frequent calls made and then to start harassing them as well? I don't have and don't want contact with my ex-husband. I'm therefore asking again please remove my name from your database I keep a clean credit record because I don't want these kind of phone calls so why must I then be harassed for somebody else's debt?