How to stop an ad playing

I open a website that supports ads, and this ad from WOTIF plays automatically. This ad follows me to any website that supports WOTIF ads and plays automatically. Is there anyway I can stop the ad from playing or stop it been linked to me as it is getting very annoying. When I open Safari in the private mode it does not happen.

I have gone into preferences and adjusted it so any video clip has to ask me to play, but it still plays.

Regards

Neil