I can't really tell what framework their using. I would assume either PHP or ASP.NET MVC.
For me Ajax is easier with ASP.NET, but that's mostly because I learned Ajax through .NET.
Use view source and you should see .php links... If you try to enter an invalid URL, you would see a link to support with .php in it.
view source doesn't show link extensions, just paths, which is why I mentioned ASP.NET MVC.
If you go to their support page, then view source, one of the links has a query string on it, and has a .php extension, so it's PHP based.