Hello.
Hello, do you need any help from us?
I would like to change my existing reservation, which is done recently.  Can you please help me out?
Sure, may I know your name please?
Thank you for considering my request. Myself Steven Carter.
Ok, please allow me a moment.
Sure, I will wait for your response.
Sorry, there is no reservation with your name in our portal to make changes.
Not an issue, anyway thank you for the information.
You are welcome, have a great day.