Оператор while ничего не делает в третьем цикле [closed]

Когда я ввожу букву D в качестве инициала третьего продавца, он не регистрирует оператор while. Сообщение об ошибке отсутствует. Он просто ничего не делает. Он будет работать, если я введу его 1-й или 2-й, но не 3-й. Неважно, капитальная она или нет.

using System;
using static System.Console;
using System.Globalization;
class HomeSales
{
   static void Main()
   {
    string response;
    double dsales;
    dsales = 0;
    double esales = 0;
    double fsales = 0;
    int initial;
    string damount;
    string eamount;
    string famount;
    double damounti;
    double eamounti;
    double famounti;
    double allsales;
    

WriteLine ("Enter a salesperson initial");
response = ReadLine();
//initial = Convert.ToInt32(response);

while (response == "d" || response == "D")
{
  WriteLine ("Enter Line of sale");
  damount = ReadLine();
  damounti = Convert.ToDouble(damount);
  dsales = dsales + damounti;
  WriteLine ("Enter a salesperson initial");
response = ReadLine();
}


while (response == "e" || response == "E")
{
  WriteLine ("Enter Line of sale");
  eamount = ReadLine();
  eamounti = Convert.ToDouble(eamount);
  esales = esales + eamounti;
  WriteLine ("Enter a salesperson initial");
response = ReadLine();
}


while (response == "f" || response == "F")
{
  WriteLine ("Enter Line of sale");
  famount = ReadLine();
  famounti = Convert.ToDouble(famount);
  fsales = fsales + famounti;
  WriteLine ("Enter a salesperson initial");
response = ReadLine();
}
if  (response == "z" || response == "Z")

{
  WriteLine("Danielle sold {0}", dsales.ToString("C", CultureInfo.GetCultureInfo("en-US")));
  WriteLine("Edward sold {0}", esales.ToString("C", CultureInfo.GetCultureInfo("en-US")));
  WriteLine("Francis sold {0}", fsales.ToString("C", CultureInfo.GetCultureInfo("en-US")));
  allsales = dsales+esales+fsales;
  WriteLine("Everybodysold {0}", allsales.ToString("C", CultureInfo.GetCultureInfo("en-US")));

}

if (dsales == esales || esales == fsales || fsales == dsales && dsales != 0 && esales != 0 && fsales !=0 )

{
  WriteLine ("There was a tie");
}
   }
}
```