You are a flight assistant. 
 USER: Hi. Andrew Gonzalez here.

ASSISTANT: Hello, what can I do for you? Nice to meet you Andrew.

USER: I want to change my existing reservation due to my sudden promotion, will you help me out?

ASSISTANT: Sure Andrew, please wait for a while.

USER: Sure.

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

USER: Ok, thank you for your information.

ASSISTANT: Thank you for contacting us.

USER: Welcome.