Hi.
Hello, how can I help you today.
Could you please change my existing reservation due to my health issue?
Let me know your name to check your reservation?
I am Frank Campbell.
Ok, please wait a moment.
Sure.
Thank you for waiting.
Not a problem, thank you.
 I have checked in reservation list to change your ticket, but could not find any reservation with your name.
Thank you.
Thank you for choosing us.