Авторизация на сайте. POST - запрос - C#

static string CheckBySite(string site_name,  string login, 
                                  string pass,       string login_style, 
                                  string pass_style, string wordtofind, 
                                  string companyname,int afterword, int count) 
        {
            String secondStepForm3 = login_style+login+pass_style+pass;
            HttpWebRequest request3 = (HttpWebRequest)WebRequest.Create(site_name);
            request3.UserAgent = ".NET Framework Test Client";// "Opera/9.80";
            request3.Method = "POST";
            request3.ContentType = "application/x-www-form-urlencoded";
            byte[] EncodedPostParams3 = Encoding.Default.GetBytes(secondStepForm3);
            request3.ContentLength = EncodedPostParams3.Length;
            request3.GetRequestStream().Write(EncodedPostParams3, 0, EncodedPostParams3.Length);
            request3.GetRequestStream().Close();
   
            HttpWebResponse response = (HttpWebResponse)request3.GetResponse();

            string lol = new StreamReader(response.GetResponseStream(), Encoding.GetEncoding("KOI8-R")).ReadToEnd();
 
            int pos = lol.IndexOf(wordtofind); //если слово "Баланс есть на странице - мы авторизовались".
            if (pos != -1)
            {
                string test = lol.Substring(pos + afterword, count); //грубо говоря получили 6-значное число. Если упадёт до 5 значного заберёт одну кавычку.
                test = test.Replace('.', ','); //заменим точку на запятую для работы с числами.
                double numVal = Double.Parse(test) / 2; // для перевода в гривны делим на 2.
                lol = companyname + ": " + numVal.ToString() + " грн.";
            }
            else
                lol = companyname + " :Something wrong with site!"; 
 
            return lol;
        }

string lds_site = "https://stat.lds.net.ua";
            string lds_login = "login";
            string lds_pass = "pass";
            string lds_login_style = "username=";
            string lds_pass_style = "&userpass=";
            string lds_word_to_find = "Баланс";
            int    lds_after_word_sym = 277;
            int    lds_balans_length = 6;
            lds_result = CheckBySite(lds_site, lds_login, lds_pass,lds_login_style,lds_pass_style,lds_word_to_find, "LDS",lds_after_word_sym,lds_balans_length);

tring life_site = "https://my.life.ua/ru/";
            string life_login = "number";
            string life_pass = "password";
            string life_login_style = "id_msisdn_code=063&id_msisdn="; //суть здесь
            string life_pass_style = "&super_password=";
            string life_word_to_find = "07.11.2014"; // дата регистрации, пофиг
            int life_after_word_sym = 277;
            int life_balans_length = 7;
            life_result = CheckBySite(life_site, life_login, 
                                     life_pass, life_login_style, 
                                     life_pass_style, life_word_to_find, "LIFE", 
                                     life_after_word_sym, life_balans_length);

<tr><td class="form-legend-auth">Логин или лицевой счет</td><td><input type="text" name="username" id="username" value="" style="width:150px" class="nt-input"></td></tr>
        <tr><td class="form-legend-auth">Ваш пароль</td><td><input type="password" name="userpass" id="userpass" style="width:150px" class="nt-input"></td></tr>

  <td>Введите ваш номер:</td>
              <td>
                <div class="phone-section">
                <select id="id_msisdn_code" name="msisdn_code" class="phone-select">
                  
                  <option value="063" >063</option>
                  
                  <option value="073" >073</option>
                  
                  <option value="093" >093</option>
                  
                </select>
                <input autocomplete="off" name="msisdn" maxlength="7" type="text" class="needValid" id="id_msisdn" />

                </div>
              </td>
            </tr>
            <tr>
              <td><label for="id_super_password">Введите Суперпароль:</label></td>
              <td>
                <div class="passwoard-section">
                  <input id="id_super_password" type="password" class="needValid noText-valid min6 password-valid" name="super_password" maxlength="6" />
                  <a href="javascript
:void(0);" class="info-link">

   static string GetCookie( string site)
        {
            string url = site;
 
            HttpWebRequest tQ = (HttpWebRequest)HttpWebRequest.Create(url);
            tQ.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8";
            tQ.UserAgent = "Mozilla/5.0 (Windows NT 5.1; rv:5.0) Gecko/20100101 Firefox/5.0";
            tQ.ContentType = "application/x-www-form-urlencoded";
            tQ.Referer = url;
            HttpWebResponse tS = (HttpWebResponse)tQ.GetResponse();
 
            string tC = tS.Headers["Set-Cookie"];
 
            Console.WriteLine(tC);
            tS.Close();
            return tC;
        }