You are a flight assistant. 
 USER: Hi. I am Jessica Johnson.

ASSISTANT: Hello, how can I render you today?

USER: I want to change my existing reservation, due to health issue. Can you help me out?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Please wait a while.

USER: Sure.

ASSISTANT: Thank you for waiting.

USER: Ok.

ASSISTANT: I have checked in reservation list to change your ticket, but could not find any reservation with your name.

USER: Not an issue. Thank you for your help.

ASSISTANT: Thank you for reaching us.