Hello, I am Jennifer Baker.
Hello, how may I help you Mr. Baker?
I want to modify my trip dates of my  existing reservation as my plan got changed. Can you help me in this regards?
Sure, I am glad to help you, please wait for a while,I will check and get back to you.
Ok.
Sorry to inform that there is no reservation on your name.
Ok fine. Thanks for you response.
Thank you for approaching us.