Scammer using my web presence.

This guy has copied my advert and uses my pictures of my site. When I called him posing as a client he told me to look at my own website and that he's the main sales rep.
http://www.gumtree.co.za/a-building-trades/parktown/drywalling-and-ceiling-contractor/1001095248160910011714009

Hi there, have you taken any action over this? Have you contacted gumtree?

The first thing I would do is post a fraud warning on your site if you haven't done so already. If he sends somebody to your site and the first thing they see is a fraud warning telling them about an impersonator, he won't get very far.