Prevent spam on Asp.NET MVC ninject website

Please see this link [login to view URL] Spam is occuring on the websites. It seems the captcha does the work, but spam is created in some other way. This is what the previous developer said: - The reason I say captcha is not part of problem is because I put some code in the page to ignore descriptions containing url ( http:// ) , but spam code contains http code. So I think spam comes through another place. My suggestion is a network proffessional should check your network and monitor your web traffic. This ways packets which comes to your server monitor carefully, so you can find out from where and through where this data comes. 1. All current spam need to be removed from database 2. New spam must be stopped