using System.Collections.Generic;
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);