In this case, all that you can do is wait and/or send another message to the advertiser. Some users may take awhile to respond, others may get so many responses that they don't reply to them all, and others may have already sold, rented or fulfilled their listing, but have not deleted their ad yet.
Unfortunately in this case, there is not much dubizzle can do to help you. Our privacy policy strictly prohibits us from releasing private contact information about the user, as well as it prohibits us from using the user's private contact information to contact them on another user's behalf.
Luckily there are many ads on dubizzle.com , and you should be able to find a comparable deal soon.