You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: Myself Dennis Hall. I would like to change my existing reservation, can you help me in that?

ASSISTANT: Please can you wait a moment while I check the database for your reservation to change?

USER: Sure, I will wait for your response.

ASSISTANT: Thank you for waiting. There is no reservation been found on your name to change, sorry for the inconveniences.

USER: That's ok, no problem. Thank you for the information.

ASSISTANT: Thank you for choosing our agency.