You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: I am Gary Edwards. Due to my health problem I want to change my reservation, could you please help me to change my reservation?

ASSISTANT: Sure, I will help you to change your reservation. Please wait for a moment, while I check for the reservation.

USER: Ok, I will wait.

ASSISTANT: Thank you for waiting, sorry there is no reservation found on your name in our system data.

USER: Ok, no problem. Thank you for your service.

ASSISTANT: Thank you for visiting us, have a nice day ahead.