You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Rachel Smith.

ASSISTANT: How can I be in your assistance today?

USER: I want to do some changes in my existing reservation. can you help me for that?

ASSISTANT: Yes, I will assist you with the change of the reservation. May I know if you can wait a moment while I check?

USER: Sure, I will wait for your response.

ASSISTANT: Thank you for waiting for my response.

USER: Ok.

ASSISTANT: Sorry, there is no reservation been found on your name to change.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for choosing our agency.

USER: Welcome.