Hi. I am Benjamin Wright.
Hello, how may I render you?
I want to change an existing reservation due to sudden change in my trip. Can you help  me out with this?
I can certainly help you.
Thank you.
Please give me a moment, I will check the reservation list and get back to you.
Ok.
We could not find any reservation by the name you provided us.
No issue. Thank you.
Thank you for approaching us.