You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello,.

USER: I am Andrew Hall.

ASSISTANT: How may I help you?

USER: I want to change my recent reservation, due to my convocation dates have been changed. Can you help me in my changing reservation?

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: No reservation found.

USER: Ok, not an issue.

ASSISTANT: Thanks.