How do I get all the HTML of this page as a string?

I'm doing a college job and so trying to read the HTML of a bradesco page ( Link I want HTML here )

The problem is that I can not get the HTML that is inside the frames and I do not know how to get it.

Currently what I'm trying to do to get the HTML is:

using System.IO;
using System.Net;

namespace ConsoleApplication1325423423423
{
public class Program
{
    private static void Main(string[] args)
    {
        string url = "https://wwwss.shopinvest.com.br/infofundos/fundos/TabelaRentabilidade.do?cdSgmtoProdt=1";

        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
        request.Method = WebRequestMethods.Http.Get;
        request.Accept = "application/json";

        WebResponse response = request.GetResponse();
        Stream dataStream = response.GetResponseStream();
        StreamReader reader = new StreamReader(dataStream);
        string responseFromServer = reader.ReadToEnd();
    }
}
}

And the return on the server response is:

Basically,whatIneedisawaytogettheHTMLinsidetheframetagwiththenamefrmMeio.

<framename="frmMeio" src="ConteudoTabelaRentabilidade.do?cdSgmtoProdt=1">