Hi.
Hello, please let me know your name?
I am Steven Phillips.
Ok Phillips, how may I help you?
I would like to change my existing reservation, so can you help me for this?
Yes, I am  happy to help you.
Thank you.
Is your previous ticket is with name Steven Phillips?
Yes.
Ok, please allow me some time to check. Sorry to inform you, there is no reservation with your name.
Oh! it is ok, thank you for your quick response.
Thank you for reaching us.