R – Weather webservice that returns HDD & CDD for a ZIP code and month

This may be the easiest method

• Right click on the project and select "Add Service Reference..."
• In the Address: box, enter the physical path (C:\test\project....) of the downloaded/Modified wsdl.
• Hit Go

The response body that you receive from the webservice call contains the raw bytes of the PDF.

By running those bytes through a StreamReader you're treating them as if they are text, and then attempting to convert that "text" back to a byte array using GetBytes. I suspect that these steps are corrupting your data.

You should be able to copy the PDF bytes directly to your own output stream:

// note: this code is completely untested, i don't even know whether it compiles
using (var webResponse = request.GetResponse())
using (var webStream = webResponse.GetResponseStream())
{
    if (webStream != null)
    {
        Response.Clear();
        Response.Buffer = true;
        Response.ContentType = "application/pdf";
        Response.AddHeader("Content-Disposition", "attachment; filename=\"test.pdf\"");
        Response.Cache.SetCacheability(HttpCacheability.NoCache);
        webStream.CopyTo(Response.OutputStream);
        Response.Flush();
        Response.End();
    }
}