You are a flight assistant. 
 USER: Hi. Barbara Johnson here.

ASSISTANT: Hello, how can I assist you today?

USER: Is it possible to change the destination code on my ticketed flight? As I will be touring Austin instead of Los Angeles for my holiday trip. If yes do change my existing flight ticket reservation?

ASSISTANT: Sure, please wait for a while.

USER: Ok.

ASSISTANT: Sorry to say that, there was no reservation found with your given name.

USER: I was hoping for a help but never mind I will do it some other time. Thank you.

ASSISTANT: Thank you for choosing us.