You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Kenneth Roberts.

ASSISTANT: How may I assist you?

USER: In my previous reservation I gave wrong airport codes, so can you help me for changing my existing reservation?

ASSISTANT: Sure, please wait a moment.

USER: Ok, I will wait for your reply.

ASSISTANT: Thanks for your time, there is no reservation found under your name.

USER: Oh! It's ok, no problem. Thank you for your services.

ASSISTANT: Ok, thanks for contacting us.