using System;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        Dictionary<string, string> keyValues = new Dictionary<string, string>()     {{"{{id}}", "1001"}, {"{{pwd}}", "123"}, {"{{date}}", "01/01/2020"}};

        string template = "Dear Member your id is {{id}} and password is {{pwd}} kindly attend on {{date}}";

        foreach (var item in keyValues)

        {

            template = template.Replace(item.Key, item.Value);

        }

​

        Console.WriteLine(template);

    }

} 

​