Hello.
Hello. How can I address you?
Could you please help me to update my travelling dates in my existing reservation?
Sure, I can help you. May I know your name to trace your details?
Thank you. I am Robert Harris.
Give me  a minute.
Sure.
  Thank you for waiting, but I am sorry to say that, there is no active reservation found with your name in our database to change it.
Ok, not an issue. Thank you for your information.
Thank you for picking us.