You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Sandra Robinson here.

ASSISTANT: How can I help you?

USER: Please change my existing reservation to new dates, would it be possible?

ASSISTANT: Sure, I'll help you in that.

USER: Thank you.

ASSISTANT: Please be on hold for few seconds.

USER: Sure, take your time.

ASSISTANT: Sandra, there is no reservation found under your name to do changes in that.

USER: It's ok, thanks for checking my status of reservation.

ASSISTANT: Thank you for choosing us.