X-www-form-urlencoded to JSON

Dim xPoslatUmo As String = ConfigurationManager.AppSettings.Item("UMOPoslat")
               If xPoslatUmo = "Ano" Then
                   Dim request As WebRequest = WebRequest.Create(ConfigurationManager.AppSettings.Item("UMOServer"))
                   request.Method = "POST"
                   Dim postdata As String = "{""GENCELEK"":""SAS_CALLC""},{""GENMSGTEXT"":""info""},{""Volat"":" + xvolat + "},{""Stav"":""" + xstav + "},{""Info"":""" + Left(xinfo, 255) + "}"
                   Dim byteArray As Byte() = Encoding.UTF8.GetBytes(postdata)
                   request.ContentType = "application/x-www-form-urlencoded"
                   request.ContentLength = byteArray.Length
                   Dim dataStream As Stream = request.GetRequestStream()
                   dataStream.Write(byteArray, 0, byteArray.Length)
                   dataStream.Close()
                   Dim response As WebResponse = request.GetResponse()
                   mlog.LogujKontroly(postdata)
                   mlog.LogujKontroly("Poslani UMO " + (CType(response, HttpWebResponse)).StatusDescription)
                   response.Close()
               Else
                   mlog.LogujKontroly("Poslani UMO  - je nastaveno neposilat")
               End If