You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I need to change my reservation due to my planned event got postponed so please help me with that.

ASSISTANT: Sure, I will help you. May I know your name?

USER: Thank you. Sure, myself Katherine Young.

ASSISTANT: Ok, please wait a minute.

USER: Sure, take your time.

ASSISTANT: I have found your previous reservation, may I know your changes. What you want to change in your previous reservation?

USER: I would like to change my airport codes and travelling dates.

ASSISTANT: Ok, please provide your trip dtaes.

USER: Sure, I need to travel on dates of 12/01 and 12/03.

ASSISTANT: May I know your airport codes?

USER: Sure, I would like to travel from SFO to LAS.

ASSISTANT: There is no flight available from SFO to LAS.

USER: Oh! It is sad to hear. Anyway, thank you for your time.

ASSISTANT: Most welcome.